— Petitioner Leopoldo Cuevas Cardenas challenges the Court of Appeals decision affirming his conviction on two counts of robbery. Prior to trial, Cardenas moved to suppress items of evidence allegedly taken in the robbery, arguing that police officers illegally entered and searched a motel room in which he was a guest. The trial court denied the motion and Cardenas was convicted. Cardenas then moved for a new trial based on the prosecutor’s failure to disclose the key witness’ impending prosecution. The trial court also denied that motion. We hold that the trial court properly denied both the motion to suppress and the motion for a new trial and affirm the Court of Appeals.
*403FACTS
The facts are taken from the trial court’s written findings of fact and undisputed testimony from the suppression hearing.
On December 6, 1998, around 11:15 p.m., the Yakima Police Department received a report of a robbery in progress. Officers Castillo and Stephens each responded separately to the location, arriving at approximately the same time and within minutes of the call.
The officers learned that two men, one “white” and one “Hispanic,” had forced their way into an apartment and robbed the two occupants. According to the occupants, the two men had taken jewelry, money, a television, and a videocassette recorder (VCR), along with some clothes, and one of the two men had been armed with either a knife or a gun. They reported that the men had fled only moments earlier in a large vehicle, similar to a Torino, with a different color passenger door, possibly orange.
Information regarding the robbery was broadcast over police radio, along with a warning that the suspects were armed and dangerous. While the officers were still at the apartment they were informed by dispatch that a security guard at the Western Motel had seen a vehicle matching the description of the suspects’ car pull into the motel parking lot. Officer Castillo testified that he responded immediately, arriving at the motel within five minutes of the call. When he arrived, Officers Scherschligt and Stephens were standing next to a brown 1970 Pontiac LeMans with a blue door, parked in front of room 8. According to Stephens, the hood of the car was still warm. He noticed some clothing items in the backseat that matched the description of the items taken, including what he thought might be a VCR. Two witnesses who were guests at the motel told police that the occupants of the vehicle had hurriedly entered room 3.
Stephens, Scherschligt, and Castillo approached room 3. All of the officers were in full uniform. Stephens testified *404that there was a three-inch gap in the curtains. He bent his knees and put his face close to the window to look inside.
Through the gap in the curtains Stephens saw two males, one Hispanic and one white, leaning over a bed sorting through papers, including credit cards. Officer Stephens knocked on the door but did not announce “police.” Officer Scherschligt was watching through the gap in the curtains and told Stephens and Castillo that the suspects darted to the back of the room following the knock.
Scherschligt and Stephens ran around the back of the motel where they saw Sergeant George. The back of the motel was fenced and Sergeant George said she had it covered. In addition, the window on the back of the motel room was too small to provide an escape route. Stephens and Scherschligt returned to the front entrance of room 3.
Before the others returned, Officer Castillo had decided to enter the room. Castillo slid the window open, and he drew the curtain aside. He looked in the window and saw both suspects but observed no weapons. Castillo then pointed his gun inside, yelled “get your hands up,” and jumped through the window. Clerk’s Papers (CP) at 53. The other officers subsequently entered, and Cardenas and. his codefendant were arrested.
ANALYSIS
A. Procedural Issues
As proponent of the motion to suppress, Cardenas had the burden of establishing that his own Fourth Amendment rights were violated by the challenged search. Rakas v. Illinois, 439 U.S. 128, 131 n.1, 99 S. Ct. 421, 58 L. Ed. 2d 387 (1978); accord Rawlings v. Kentucky, 448 U.S. 98, 104, 100 S. Ct. 2556, 65 L. Ed. 2d 633 (1980); United States v. $277,000.00 U.S. Currency, 941 F.2d 898, 901 (9th Cir. 1991); State v. White, 97 Wn.2d 92, 110 n.9, 640 P.2d 1061 (1982); State v. Murray, 110 Wn.2d 706, 714, 757 P.2d 487 (1988). This burden arises only if the defendant’s standing to claim a privacy violation has been challenged. If the issue *405of standing is not raised to the trial court, it may not be considered on appeal. Tyler Pipe Indus., Inc. v. Dep’t of Revenue, 105 Wn.2d 318, 327, 715 P.2d 123 (1986); see also Baker v. Baker, 91 Wn.2d 482, 484, 588 P.2d 1164 (1979).
Although the State questioned Cardenas’ standing to challenge the search in the Court of Appeals, the State did not raise the issue of standing to the trial court nor did it file an answer or a cross-petition for review in this court. Accordingly, we decline to consider the issue. RAP 13.4(d), 13.7(b). State v. Bobic, 140 Wn.2d 250, 258, 996 P.2d 610 (2000) (citing Tuerk v. Dep’t of Licensing, 123 Wn.2d 120, 124, 864 P.2d 1382 (1994)); see also Estate of Jordan v. Hartford Accident & Indem. Co., 120 Wn.2d 490, 496, 844 P.2d 403 (1993) (citing RAP 13.7(b)).
B. Exigent Circumstances
Nonconsensual entry and search of property is governed by the warrant requirements of the Fourth and Fourteenth Amendments. Michigan v. Clifford, 464 U.S. 287, 293, 104 S. Ct. 641, 78 L. Ed. 2d 477 (1984); State v. Leach, 113 Wn.2d 735, 738, 782 P.2d 1035 (1989); Staats v. Brown, 139 Wn.2d 757, 991 P.2d 615 (2000). Additionally, Washington Constitution, article I, section 7, provides that “[n]o person shall be disturbed in his private affairs, or his home invaded, without authority of law.” A warrantless search is unreasonable as a matter of law unless the State establishes that one of a very narrow set of exceptions applies. Leach, 113 Wn.2d at 738. Although ordinarily warrantless entries are presumptively unreasonable, warrant requirements must yield when exigent circumstances demand that police act immediately. Warden, Md. Penitentiary v. Hayden, 387 U.S. 294, 298-99, 87 S. Ct. 1642, 1645-46, 18 L. Ed. 2d 782 (1967); State v. Terrovona, 105 Wn.2d 632, 644, 716 P.2d 295 (1986) (citing Dorman v. United States, 435 F.2d 385, 392-93 (D.C. Cir. 1970)).
In this case, Cardenas challenges the trial court’s conclusion that exigent circumstances justified the warrantless entry into the motel room in which he was a guest.
*406This court uses six factors as a guide in determining whether exigent circumstances justify a warrantless entry and search: (1) the gravity or violent nature of the offense with which the suspect is to be charged; (2) whether the suspect is reasonably believed to be armed; (3) whether there is reasonably trustworthy information that the suspect is guilty; (4) there is strong reason to believe that the suspect is on the premises; (5) a likelihood that the suspect will escape if not swiftly apprehended; and (6) the entry is made peaceably. Terrovona, 105 Wn.2d at 644. The trial court considered these factors and found that exigent circumstances justified the officers’ entry. The Court of Appeals agreed. Cardenas does not assign error to the trial court’s factual findings. Therefore, they are verities on appeal. State v. Hill, 123 Wn.2d 641, 644, 870 P.2d 313 (1994).
Specifically, the court found: (1) first degree robbery committed with a weapon is a grave offense; (2) the suspects were believed to be armed with either a knife or a gun; (3) the police had trustworthy information that the suspects had committed the crime because the men matched the description given by the victims, the car matched the description, and two witnesses saw two men run from the car in a hurry; (4) the police had strong reason to believe the suspects were inside the room because two witnesses said they saw the men from the car run inside room 3; (5) even though the danger of escape was not great, the officers reasonably believed that it was possible because the suspects darted to the back of the room when the police knocked; and (6) although the entry was not entirely peaceable, the potential for harm was fairly low.
Cardenas argues that the court’s findings of fact do not support the trial court’s conclusion that a warrantless entry was justified. He points out that Cardenas’ vehicle was a 1970 Pontiac LeMans, brown with a blue door. The victims had described the suspect vehicle as brown with possibly an orange door. He further contends that, although there were clothing items that matched the description of those taken *407in the robbery and possibly a VCR, the contents of the vehicle were unremarkable. Perhaps most importantly, Cardenas argues that the officers’ observations of the two persons in the motel room cannot be considered in determining whether exigent circumstances existed because the observations were illegally obtained.
We review the conclusions of law entered in connection with a suppression order de novo. State v. Mendez, 137 Wn.2d 208, 970 P.2d 722 (1999). Even assuming the validity of Cardenas’ claims, the trial court’s conclusion that exigent circumstances existed is nonetheless correct. Although Cardenas does not take issue with factors (1) and (2), we agree with the trial court’s conclusion that a serious felony, armed robbery, had been committed and that the officers had reason to believe the suspects may have been armed. We also agree with the trial court that factor (3) is satisfied. As the trial court noted in its factual findings, officers responded to the robbery scene within minutes of the incident. The victims reported they had just been robbed by two men. They gave a description of the items taken and the suspect vehicle. Shortly after broadcasting that information, police received a call from the Western Motel reporting the arrival of the suspect vehicle. While the vehicle did not have an orange door, it substantially matched the description given by the victims. It was a large, brown American car with a different color passenger door. Officers arrived at the motel within minutes of the report and located the vehicle. Its hood was still warm. The officers testified that the contents of the backseat matched the description of property taken from the victims. Although the items taken in isolation may not have been unusual, their presence under the circumstances permits a reasonable inference that the items were the same ones taken in the earlier robbery. Additionally, two witnesses at the motel had seen two men hurrying from the car into room 3.
Accordingly, we find that the court’s conclusion on factor (3) is supported by the court’s findings. Similarly, factor (4) is satisfied based on the findings as recited above.
*408Apart from the officers’ observations made through the parted curtain, there is little to support the conclusion that the suspects were likely to escape unless swiftly apprehended. Thus, without the observations made by officers through the curtain opening, factor (5) is doubtful. Nevertheless, it is not necessary that every factor be met to find exigent circumstances, only that the factors are sufficient to show that the officers needed to act quickly. See, e.g., State v. Patterson, 112 Wn.2d 731, 736, 774 P.2d 10 (1989) (no one factor is conclusive; weight varies with circumstances); State v. Flowers, 57 Wn. App. 636, 789 P.2d 333 (1990) (fact that some factors not present is not controlling). Finally, factor (6) is satisfied here. Police were in full uniform and yelled, “get your hands up,” placing the occupants on notice that the intruders were law enforcement officers, thus reducing the potential for violence. CP at 53. Additionally, the police did not break down the door but entered through an unlocked window. As the trial court found, the potential for harm was low. Weighing the Terrovona factors, we conclude that exigent circumstances justified the entry in this case, even if we accept Cardenas’ claims.
Turning to those claims, however, we first address Cardenas’ contention that the officers’ observation through the parted window curtains was unlawful. The Court of Appeals applied the “open view” doctrine and found that no search had occurred.
Under the open view doctrine, if an officer detects something by using one or more of his or her senses, while lawfully present at the vantage point where those senses are used, no search has occurred. State v. Rose, 128 Wn.2d 388, 393, 909 P.2d 280 (1996); see also State v. Young, 123 Wn.2d 173, 867 P.2d 593 (1994); State v. Seagull, 95 Wn.2d 898, 901, 632 P.2d 44 (1981). In Seagull, this court found that an officer has the same license to intrude as a reasonably respectful citizen. Seagull, 95 Wn.2d at 902 (citing United States v. Vilhotti, 323 F. Supp. 425, 431 (S.D.N.Y.), aff’d in part, rev’d in part, 452 F.2d 1186 (2d Cir. 1971)); see Rose, 128 Wn.2d at 396. However, a “particularly intrusive *409method of viewing, will. . . intrude upon a constitutionally protected expectation of privacy.” 95 Wn.2d at 903.
Although there is no case directly on point, courts have overwhelmingly found that an attempt to block a view through a window shows a reasonable expectation of privacy. See, e.g., State v. Jordan, 29 Wn. App. 924, 631 P.2d 989 (1981) (by drawing curtains, individuals inside duplex had clearly demonstrated a reasonable expectation of privacy); State v. Morris, 27 Kan. App. 2d 155, 999 P.2d 283 (2000) (defendant demonstrated reasonable expectation of privacy by closing blinds); Lorenzana v. Superior Court, 9 Cal. 3d 626, 511 P.2d 33, 108 Cal. Rptr. 585 (1973) (petitioner exhibited reasonable expectation of privacy by drawing window shade even with two-inch gap between blinds and sill); Pate v. Mun. Court, 11 Cal. App. 3d 721, 89 Cal. Rptr. 893 (1970) (defendants exhibited reasonable expectation of privacy drawing motel room window curtains to avoid observations from area open to public).
Similarly, courts have consistently found that a defendant who fails to block the view through a window in some way does not have a reasonable expectation of privacy. See, e.g., Rose, 128 Wn.2d at 393 (no search when police, lawfully on front porch, looked through unobstructed window next to front door); People v. Superior Court, 264 Cal. App. 2d 165, 70 Cal.Rptr. 362 (1968) (officers did not engage in search when they looked through undraped window); State v. Drumhiller, 36 Wn. App. 592, 675 P.2d 631 (1984) (defendants sitting in front of window with drapes open four to six feet wide had no reasonable expectation of privacy); Sayre v. State, 471 N.E.2d 708 (Ind. Ct. App. 1984) (defendants did not exhibit reasonable expectation of privacy by leaving curtains open); Commonwealth v. Hernley, 216 Pa. Super. 177, 263 A.2d 904 (1970) (must close curtains to preserve privacy); People v. Hicks, 49 Ill. App. 3d 421, 364 N.E.2d 440, 7 Ill. Dec. 279 (1977) (upholding police observations through undrawn curtains); State v. Thompson, 196 Neb. 55, 241 N.W.2d 511 (1976) (upholding observations through sheer curtains); State v. Clark, 124 Idaho *410308, 859 P.2d 344 (1993) (use of sheer curtains does not create a legitimate expectation of privacy).
Here, Cardenas was in a motel room in which the curtains were partially closed, leaving a three-inch gap. However, failure to completely close the curtains is not necessarily determinative. See, e.g., Jordan, 29 Wn. App. 924 (the fact occupants had not succeeded in completely closing curtains did not diminish the reasonableness of their expectation of privacy); State v. Wooding, 117 N.C. App. 109, 449 S.E.2d 760 (1994) (three- to four-inch opening in drawn curtains does not eliminate reasonable expectation of privacy); but see State v. Brown, 9 Wn. App. 937, 515 P.2d 1008 (1973) (defendant lost expectation of privacy in motel room when he opened but failed to completely close curtains); United States v. Fields, 113 F.3d 313, 321 (2d Cir. 1997) (defendants did not have reasonable expectation of privacy when they left five- to six-inch gap in blinds).
The circumstances here, including the fact that the officers were required to peer through the opening on bended knees, present a close question. However, in light of our conclusion that exigent circumstances existed without those observations, we need not decide whether the open view doctrine applies to the officers’ observations. Rather, we find that the officers’ view through the window was justified by officer safety concerns. When exigent circumstances justify a warrantless entry, police officers are not required to proceed at their peril. Police officers are justified in taking reasonable actions to secure their safety when entering a premise under exigent circumstances. See, e.g., Terry v. Ohio, 392 U.S. 1, 23, 88 S. Ct. 1868, 20 L. Ed. 2d 889 (1968) (unreasonable to expect police officers to take unnecessary risks in performance of duties); Michigan v. Long, 463 U.S. 1032, 1052 n.16, 103 S. Ct. 3469, 77 L. Ed. 2d 1201 (1983) (unreasonable to prevent police from taking reasonable steps to protect their safety); City of Seattle v. Hall, 60 Wn. App. 645, 652, 806 P.2d 1246 (1991) (officers may take necessary precautions to protect themselves and others from potentially dangerous situations). Such safety precau*411tions as the officers took here are necessary to ensure that officers are not injured or killed in the course of their entry.
C. Knock and Announce Rule, RCW 10.31.040
In addition to the constitutional prohibitions on warrant-less entries, Washington has codified the procedures that officers must follow when entering a premises. Pursuant to RCW 10.31.040, the “knock and announce rule,” police officers are required to knock, announce their identity and purpose, and wait a reasonable period to give occupants opportunity to voluntarily admit them before entering premises without permission. The State asserts that the trial court found that Officer Castillo substantially complied with RCW 10.31.040. That is incorrect. The trial court found “[c]learly, under normal circumstances, absent exigent circumstances, the conduct here of the police would not be accepted.” CP at 52-53 (Findings of Fact and Conclusions of Law Following Suppression Hearing). We agree. Officer Castillo slid the window open, pushed aside the curtain, pointed his gun inside and yelled, “[g]et your hands up!” CP at 53. He then jumped through the window. He did not give the occupants time to open the door voluntarily. The trial court properly concluded that the officers failed to comply with the provisions of RCW 10.31.040.
The purpose of the knock and announce statute is: (1) to reduce potential violence, which might arise from an unannounced entry, (2) to avoid unnecessary property destruction, and (3) to protect an occupant’s right to privacy. State v. Myers, 102 Wn.2d 548, 554, 689 P.2d 38 (1984). Strict compliance with the knock and announce rule is required unless the State can demonstrate that the police had “a reasonable suspicion that knocking and announcing their presence, under the particular circumstances, would be dangerous or futile, or that it would inhibit the effective investigation of the crime by, for example, allowing the destruction of evidence.” Richards v. Wisconsin, 520 U.S. 385, 394, 117 S. Ct. 1416, 137 L. Ed. 2d 615 (1997). In State v. Richards, 136 Wn.2d 361, 962 P.2d 118 (1998), this court *412held that compliance with the knock and announce rule is required unless exigent circumstances exist or compliance would be futile. See also State v. Carson, 21 Wn. App. 318, 584 P.2d 990 (1978) (presence or absence of exigent circumstances sufficient to constitute an exception to the knock and wait rule is factual determination to be made by trial court); State v. Young, 76 Wn.2d 212, 217, 455 P.2d 595 (1969); State v. Edwards, 20 Wn. App. 648, 581 P.2d 154 (1978); State v. Woodall, 32 Wn. App. 407, 647 P.2d 1051 (1982) , rev’d on other grounds, 100 Wn.2d 74, 666 P.2d 364 (1983) .
Here the officers reasonably believed that the suspects were armed. They were aware that the suspects had used physical force against the robbery victims, including holding a pair of scissors against one of the victim’s throat. Additionally, the officers had observed the suspects rushing toward the back of the motel room following their knock and had reason to think they might be attempting escape. Further, some of the evidence included jewelry, money, and credit cards, which could have been easily disposed of. Finally, the officers entered by first sliding open a window so there was no property destruction. We agree with the trial court that compliance with RCW 10.31.040 was excused under these circumstances.
D. Failure to Disclose Pending Criminal Charge
Cardenas contends that the State’s failure to disclose that one of its key witnesses (Ausencio Diaz) had been charged with possession of stolen property denied him the opportunity to impeach the witness. Therefore, he argues, the trial court erred by denying his motion for a mistrial. The grant or denial of a motion for a new trial is within the sound discretion of the trial court and will be reversed only for abuse of that discretion. State v. Copeland, 130 Wn.2d 244, 294, 922 P.2d 1304 (1996). A trial court abuses its discretion when the reason for its decision is manifestly unreasonable or based upon untenable grounds. Davis v. Globe Mach. Mfg. Co., 102 Wn.2d 68, 77, 684 P.2d 692 *413(1984). Because possession of stolen property is a crime of dishonesty affecting credibility, Cardenas argues that under ER 608(b) and ER 609 he could have used the information for impeachment thereby possibly changing the outcome of the trial. He correctly observed that the prosecutor has a duty to disclose any criminal record or prior criminal convictions of state’s witnesses. CrR 4.7(a)(1)(vi).
The Court of Appeals found that the State’s disclosure duty includes informing the defense of a pending charge against a state witness but that disclosure here would not have changed the outcome of the trial. The court found that other evidence introduced at trial was sufficient to allow the jury to question Diaz’s credibility, including the fact that he was on probation and that another witness testified that Diaz sold drugs and often accepted stolen property in exchange for drugs.
We agree that disclosure here would not have affected the outcome of the trial because the information could not have been used for impeachment purposes as contemplated by Cardenas. Although Cardenas relies on State v. McKinsey, 116 Wn.2d 911, 913-14, 810 P.2d 907 (1991) for authority that the existence of a pending charge is proper impeachment evidence, his reliance is misplaced. McKinsey involved a conviction rather than a pending charge. Moreover, while a conviction is probative of credibility and admissible for impeachment purposes under ER 609(a), a charge is not. Similarly, an arrest without a conviction is usually inadmissible for impeachment under ER 608. The comment to ER 608(b) notes that generally “acts of misconduct not the subject of a prior conviction have not been admissible for impeachment purposes.” See ER 608(b) cmt. at 168. See also 5A Karl B. Tegland, Washington Practice: Evidence Law and Practice §§ 608.6, at 362; 609.3, at 394-95 & n.1 (4th ed. 1999) (noting a mere arrest without conviction is inadmissible for impeachment).1 Accordingly we find the trial court did not abuse its discretion in denying a new trial.
*414CONCLUSION
We hold that the trial court properly concluded that exigent circumstances excused the warrantless entry in this case. Likewise, we hold that the officers’ observations through the motel room window were justified because of concerns for officer safety. We hold that due to the danger of potential violence and destruction of evidence, the officers were not required to knock and announce before entry. Finally, we hold that the trial court did not abuse its discretion in denying the motion for a new trial because the evidence of the pending criminal charge would not have been admissible.
Smith, Ireland, Bridge, and Owens, JJ., concur.
The ER 608(b) prohibition against admitting evidence of prior conduct does not apply if the specific instances of conduct are offered to show witness bias. 5A *414Tegland supra, at 353. Here, Cardenas does not argue that he was denied an opportunity to explore a witness’ bias under the confrontation clause. See Davis v. Alaska, 415 U.S. 308, 316, 94 S. Ct. 1105, 39 L. Ed. 2d 347 (1974).