Pursuant to D.C. Code § 23-104(a)(l) (1981) the United States appeals from the grant of a motion to suppress physical evidence and statements. It contends that since an anonymous tip justified an investigative stop under Terry v. Ohio, 392 U.S. 1, 88 S.Ct. 1868, 20 L.Ed.2d 889 (1968), the police had a right to search containers which might hold weapons, and that the statements were not obtained during custodial interrogation in violation of Miranda v. Arizona, 384 U.S. 436, 86 S.Ct. 1602, 16 L.Ed.2d 694 (1966). We agree that the physical evidence should not have been suppressed but remand for findings of fact on whether the statements occurred during custodial interrogation.
I.
Appellee Johnson was charged with carrying a pistol without a license and possession of an unregistered firearm, D.C. Code §§ 22-3204, 6-2311(a). At the suppression hearing Detective Israel testified that on March 22, 1986, he responded around 10:00 a.m. to a police radio run that a man sitting inside a Volkswagen at the corner of 23rd and Savannah Streets, S.E., was selling handguns or weapons. The information came from an anonymous phone call to the Communications Division of the Metropolitan Police Department. According to Officer Jeffrey Blevins, who arrived on the scene shortly after Detective Israel, the broadcast was for “a subject trying to sell a gun out of an orange Volkswagen that was parked in the area of 23rd and Savannah Street.”
Detective Israel reached the corner of 23rd and Savannah Streets within fifteen seconds of receiving the radio run and saw two men sitting in the front seat of an orange Volkswagen; no other cars were *1091parked nearby. The Volkswagen was parked fifty feet or less from the comer, and appellee was seated in the passenger seat. The detective parked directly behind the Volkswagen, activated his “red light” to identify himself as a police officer, and, after giving the dispatcher the license plate number and a description of the Volkswagen, approached the driver’s side of the car. He identified himself as a police officer, and to further ensure his safety, he told the two men to put their hands in plain sight. The detective kept his eyes on their hands, and did not see anything else in the car; from his position behind the driver he did not have a full view of the front of the car. Less than a minute later, as two other officers arrived in a marked police car, appellee got out of the Volkswagen. The detective frisked the man in the driver’s seat, and upon finding no weapon, took him to the rear of the car, where appellee and another officer were standing. The third officer looked into the open front door on the passenger side of the Volkswagen and said that he had found a handgun. The detective then walked to the passenger side of the Volkswagen, looked inside, and saw a gun lying on some clothes which were inside a fully open gym bag on the passenger seat.
In response to the detective’s questions, both men denied that they owned the bag or the gun. The detective also asked who owned the Volkswagen and what they were doing in the car; they denied ownership of the car and said that they were just talking. The detective did not ask any other questions, and did not hear the men make any other statements. Appellee was then formally arrested.1
The trial judge granted appellee’s motion to suppress on the ground that the police lacked the “articulable suspicion” required to justify a Terry stop, and hence did not have the right to approach the car, search the passengers and containers in the car, or question the passengers. The judge focused on the informant’s refusal to identify himself in concluding that the mere presence of a vehicle matching the informant’s description was, without further indicia of criminal activity, insufficient corroboration of the tip.
II.
In Terry, supra, the Supreme Court set out “a narrowly drawn authority to permit a reasonable search for weapons for the protection of the police officer, where he has reason to believe that he is dealing with an armed and dangerous individual, regardless of whether he has probable cause to arrest the individual for a crime.” 392 U.S. at 27, 88 S.Ct. at 1883. Such searches must be based on “specific and articulable facts” which would lead a reasonable police officer at the moment of the search to conclude that the action taken was appropriate. Id. at 21-22, 88 S.Ct. at 1880. Accordingly, we must decide whether the informant’s tip justified a Terry stop or was “completely lacking in indicia of reliability, [and] would either warrant no police response or require further investigation before a forcible stop of a suspect would be authorized.” Adams v. Williams, 407 U.S. 143, 147, 92 S.Ct. 1921, 1924, 32 L.Ed.2d 612 (1972).2 We hold that Detective Israel had articulable suspicion for making an investigatory Terry stop.
Anonymous tips, in the absence of sufficient corroboration, present the prospect of governmental incursions into people’s lives which would greatly expand the limited Terry exception to the probable cause requirement of the fourth amendment. To avoid such abuse, each case must be carefully evaluated on its facts. Prompt police investigation of tips involving guns is often included in the equation of determining the *1092reasonableness of police conduct. See, e.g., United States v. McClinnhan, 212 U.S. App.D.C. 368, 660 F.2d 500 (1981); cf. Derrington v. United States, 488 A.2d 1314 (D.C.1985) (exigent circumstances). We conclude the reasonableness of Detective Israel’s response was demonstrated.3
The tip in the instant case provided detailed information about the precise location where the suspect could be found and suggested an on-going crime involving the sale of a gun or guns. A police officer could reasonably interpret the tip as suggesting ongoing gun trafficking between a seller and a buyer inside of the Volkswagen. The absence of a visible gun prior to the Terry stop or other indication of possible criminality directly observed by Detective Israel is not dispositive of whether corroboration of the physically restrictive setting of the alleged criminal activity and the presence of two people in the front seats within seconds after receipt of the radio run provided articulable suspicion for making a Terry stop.
In view of the virtually immediate corroboration of all the innocent circumstances, the detective did not have to wait until he saw a gun to conclude that it was reasonable for him to investigate further. Because the suspects were in a car, the detective could reasonably assume that from his vantage point as he approached the Volkswagen from the rear, he would be unable to observe a sale taking place in the front of the car or to overhear any conversations. Furtive action or other suspicious movement by either of the men in the Volkswagen also was unlikely to fall within the detective’s line of vision. The potential mobility of the car, moreover, would have suggested to a reasonable police officer that closer observation of the two men or delayed investigation risked the recovery of any gun. See Chambers v. Maroney, 399 U.S. 42, 51-52, 90 S.Ct. 1975, 1981, 26 L.Ed.2d 419 (1970); Carroll v. United States, 267 U.S. 132, 158-59, 45 S.Ct. 280, 287, 69 L.Ed. 543 (1925). Consequently, once Detective Israel verified that the circumstances were fully consistent with the tip, he reasonably could conclude that there was little, if anything, to gain and more to lose by a period of observation and that it was important to determine promptly if the suspect had a gun.
In Terry, the Supreme Court held: [W]here a police officer observes unusual conduct which leads him reasonably to conclude in light of his experience that criminal activity may be afoot and that the persons with whom he is dealing may be armed and presently dangerous, where in the course of investigating this behavior he identifies himself as a policeman and makes reasonable inquiries, and where nothing in the initial stages of the encounter serves to dispel his reasonable fear for his own ... safety, he is entitled for the protection of himself ... to conduct a carefully limited search of the outer clothing of such persons in an attempt to discover weapons which might be used to assault him.
392 U.S. at 30, 88 S.Ct. at 1884-85. Thus, the officer must have grounds for concluding that criminal activity may be afoot and only then may conduct a protective search. Id. at 20, 88 S.Ct. at 1879. This two-pronged test is readily adaptable to a situation involving an anonymous tip concerning a gun sale by a man inside of an automobile. As in the instant case, the tip itself provided the direct observation of unusual conduct and suggested the dangerousness of the situation. Cf. McClinnhan, supra, 212 U.S.App.D.C. at 373, 660 F.2d at 505. Therefore, upon corroborating so much of the tip as was possible under the circumstances, Detective Israel could justifiably rely on his experience in concluding that he had observed, through the tipper’s observations, unusual conduct that indicated that criminal activity “may be afoot.” Only after verifying all aspects of the tip except an actual sale of a gun did he confront the two men in the Volkswagen. He then identified himself, took reasonable steps to avoid danger to himself in the event either *1093man had a gun, and asked questions to determine whether they were engaged in criminal activity. To this extent the detective’s action was comparable to that of the officer in Terry, supra, 392 U.S. at 6-7, 88 S.Ct. at 1872.
In Terry, the police officer observed the innocent circumstances of two men walking back and forth on the street in front of a store until the officer was satisfied that it was reasonable to conclude that the men were “casing a job, a stick up.” At that point further observation would have been useless since the officer could not overhear the men’s conversation and was not required to continue his observation until he saw an activity which could only be consistent with criminal conduct. It was not inconceivable that the men were merely waiting for a friend to get off from work at the store. Indeed, the two men were leaving the area when the officer confronted them. Nevertheless, the Court did not interpret the fourth amendment to require that the officer defer confronting the men where, based on his experience as a police officer, the officer reasonably could conclude that the men were preparing to commit a robbery. Although the officer’s direct observations were significant in providing articu-lable suspicion that “casing” was occurring, the Court did not suggest other means of conveying information to a police officer would be unacceptable. Nor did the Court place limits on the amount of time that was required for constitutionally adequate police investigation, recognizing the infinite variety of police confrontations with citizens that might occur. Rather the Court focused on the officer’s factual basis for acting in light of his experience and on the nature and quality of the intrusion on individual rights. Id. at 24-27, 88 S.Ct. at 1881-83.
A review of our decisions on anonymous tips is useful in gauging whether the facts in the instant case meet the constitutional threshold. We are satisfied upon so doing that the anonymous tip in the instant case provided no less information than such tips in other cases in which this court has upheld Terry stops.
In United States v. Mason, 450 A.2d 464, 465 (D.C.1982), a radio run based on an anonymous tip was for a man standing at a specified corner, dressed in a certain manner and carrying a black tote bag containing a gun. This court held that when the officer observed the subject less than two minutes later standing twenty yards from the corner, dressed in substantially the manner described and carrying a tote bag, the police officer was entitled to conduct a Terry stop. Police officers might reasonably believe they are in danger based on “[a]n anonymous tip concerning a man in possession of a gun, where all innocent details have been quickly corroborated on the scene.” Id. at 466. Noting that the officer had no suitable or safe alternative to securing and opening the bag, the court also reversed the suppression of the bag and its contents.
The instant case is similar to Mason: in both cases the tip provided information concerning the location of a suspect with a gun. In one the suspect’s clothing was described; in the other case the make and color of the car in which the suspect was sitting were described. The probative value of these descriptions is similar. Neither carries as much weight as fingerprints or other uniquely identifying characteristics, since people can exit cars and can discard or change articles of clothing. Still, the stop was upheld in Mason even though no additional action by the defendant was observed by the police officer until he had confronted the defendant with the information in the radio run. Id. at 465. Similarly, when Detective Israel arrived on the scene, in far less time than the officer in Mason, the information concerning the car was fully corroborated,4 and the tip would only have fit someone inside of the car notwithstanding the absence of details about the *1094description of the seller’s personal characteristics and clothes.
In Lawson v. United States, 360 A.2d 38 (D.C.1976), this court affirmed the denial of a motion to suppress where the police received an anonymous tip that a man with a grey beard wearing blue jeans and standing at a telephone booth on a certain street comer was carrying a pistol in his pocket. When the police arrived three minutes later, they saw a man fitting the description in the phone booth and no other people nearby. The gun was not visible until the police frisked defendant. The court held that the tip’s “[reliability was established when the police just minutes later reached the street corner, and found that the scene corroborated the informant’s report in all respects.” Id. at 40. The court viewed the tip as being made by an eyewitness citizen-informer, id.; it did not contain a greater quantum of information than the tip in the instant case, where the information was corroborated in less time.5 Lawson differs only to the extent that an officer testified that as he and his partner approached the defendant, the defendant made motions which looked “as though he was trying to hide something.” Id. at 39. Although the defendant’s response to the officers’ approach was one factor relied upon by the court in determining that the investigatory stop was reasonable, the court held that the tip’s reliability had been established before the furtive gesture was made. Reliability was established as soon as the police arrived on the scene and found that the innocent details of the tip were corroborated. Id. at 40.
In the instant case the trial judge ruled that the tip’s reliability could not be sufficiently established for Terry purposes because it was anonymous, and hence the detective should have waited until he saw some plainly illegal conduct rather than relying on the corroboration of innocent details alone. Our decisions make clear, however, that anonymous tips may furnish the requisite articulable suspicion. Mason, supra, 450 A.2d at 466. A police officer may lawfully approach a described suspect once innocent details of an anonymous tip are promptly corroborated, and is not, under all circumstances, required to wait until something more indicative of illegal conduct occurs.
Nothing in the record before us suggests that the tip in the instant case was made other than by a citizen who had observed gun trafficking.6 The possibility that the person giving information to the police is a disgruntled citizen or has a motive to falsify is insufficient to preclude a Terry investigation where the reliability of the anonymous report of an ongoing crime is enhanced by immediate verification of all its innocent details. See, e.g., Groves, supra note 5, 504 A.2d at 604; Lawson, supra, 360A.2dat40; Galloway v. United States, 326 A.2d 803, 805 (D.C.1974), cert. denied, 421 U.S. 979, 95 S.Ct. 1981, 44 L.Ed.2d 471 (1975).
Since we hold the police had the requisite articulable suspicion under Terry, and no gun was found on either of the two men, the police could properly search the passenger compartment of the car for weapons, including containers of a size likely to contain a weapon. Michigan v. Long, 463 U.S. *10951032, 1049, 103 S.Ct. 3469, 3480, 77 L.Ed.2d 1201 (1983) (search of passenger compartment of car, limited to areas in which a weapon may be placed or hidden, is permissible if officer has articulable suspicion that suspect is armed and dangerous); Johnson v. United States, 350 A.2d 738 (D.C.1976); United States v. Thomas, 314 A.2d 464 (D.C.1974); McClinnhan, supra, 212 U.S.App.D.C. 368, 600 F.2d 500. The sole justification for such searches is to protect the police officers involved and not the collection and preservation of evidence. Michigan v. Long, supra, 463 U.S. at 1049 n. 14, 103 S.Ct. at 3481 n. 14. The trial judge did not make a finding on whether the gun was in plain view, but since the police could have searched the gym bag even if the gun was not in plain view, we do not need to remand for a finding on this issue, and hold that the tangible evidence should not have been suppressed.
Appellee also contended that his statements to the police should have been suppressed under Miranda v. Arizona, supra, 384 U.S. 436, 86 S.Ct. 1602. Because the trial judge found that the officers lacked articulable suspicion to make a Terry stop, he did not determine whether the police questioning constituted custodial interrogation. The record is silent on potentially significant circumstances, see, e.g., Miley v. United States, 477 A.2d 720, 722-23 (D.C.1984). Accordingly, we remand the case to the trial judge to make findings on whether appellee was subjected to custodial interrogation. See Staton v. United States, 466 A.2d 1245, 1253 (D.C.1983).
Affirmed in part, reversed in part, and remanded.
. Officer Blevins also testified as a defense witness that, according to the report he prepared concerning the arrest, appellee did not make any statements to him (Blevins) regarding the gun, and the gun was "sitting on the passenger seat in plain view.”
. In reviewing the trial court’s determination, the appellate court’s role is to ensure that the trial court had a substantial basis for concluding articulable suspicion existed. See Illinois v. Gates, 462 U.S. 213, 238-39, 103 S.Ct. 2317, 2332, 76 L.Ed.2d 527 (1983) (discussing probable cause).
. Appellee’s reliance on United States v. Walker, 115 Daily Wash.L.Rptr. 1433 (D.D.C. July 13, 1987) is misplaced. The question before the District Court concerned probable cause rather than articulable suspicion, and the tip did not involve a gun.
. Appellee Johnson misstates the issue in an attempt to distinguish Mason. In his brief, he states erroneously that the tip was not of an ongoing crime, and that the car was not where the informant said it was. The issue is whether a reasonable police officer could have interpreted the tip as describing what he saw.
. While many other cases also involve informants, Mason and Lawson are factually closest to the instant case. See Adams v. Williams, 407 U.S. 143, 92 S.Ct. 1921, 32 L.Ed.2d 612 (1972) (person known to police officer approached him in person and told him man sitting in nearby car had drugs and a gun); Groves v. United States, 504 A.2d 602 (D.C.1986) (tip reliable because informant called twice, identified himself, and was clearly observing the scene firsthand); Allen v. United States, 496 A.2d 1046 (D.C.1985) (anonymous tip sufficient to establish probable cause where caller was known to police, her previous calls had led to several drug seizures, and several details of the tip were corroborated); United States v. Walker, 294 A.2d 376 (D.C.1972) (man who refused to give his name told two police officers a man named Willie, who was dressed in a certain manner and had an artificial leg, was sitting on the porch of a house in a certain block and had a gun); Murphy v. United States, 293 A.2d 849 (D.C.1972) (anonymous tip that a man named Murphy, of a certain description and wearing certain clothing, had a gun, and was sitting at a particular booth in Good Guys restaurant).
. Appellee concedes the tip was made by an anonymous unpaid informer.