While a passenger on a bus en route from Augusta to Atlanta, appellant-plaintiffs’ son was shot to death in a sudden and unprovoked criminal assault by a co-passenger. As a result, plaintiffs filed the instant wrongful death action against appellee-defendants, the corporation which operated as a common carrier and its agent. After discovery, defendants moved for summary judgment and the trial court granted the motion. Plaintiffs appeal.
Plaintiffs assert several theories of liability against defendants. Defendants admitted that the applicable industry and regulatory rules prohibit the transportation of loaded firearms on a common carrier. By way of enforcing this rule, defendants conducted only a visual inspection of passengers as they boarded the bus. First, plaintiffs assert that defendants breached the duty of extraordinary care imposed upon common carriers for the safety of passengers by failing to take precautions, beyond the mere visual inspection of boarding passengers, to prevent a passenger from boarding a bus while in possession of a gun. To support the argument that additional precautions were reasonably necessary in this case, plaintiffs argue the unreasonable risk of harm to passengers from violent crimes was foreseeable by virtue of prior substantially similar crimes. Knowledge of the unreasonable risk of criminal attack upon persons to whom a duty of care is owed “may be demonstrated by evidence of the occurrence of prior substantially similar incidents.” Savannah College of Art & Design v. Roe, 261 Ga. 764, 765 (409 SE2d 848) (1991). See also Lau’s Corp. v. Haskins, 261 Ga. 491 (1) (405 SE2d 474) (1991); MARTA v. Allen, 188 Ga. App. 902 (374 SE2d 761) (1988). Even though the cited cases involved premises liability, we see no reason why the rule of these cases must be confined to knowledge of a dangerous static condition *224on real property, as proposed by the dissenting opinion. Thus, we see no reason why this rule is not applicable to the duty of care owed to passengers by a common carrier.
Defendants argue plaintiffs presented no evidence of any substantially similar incidents since no other reported case exists in which one of defendants’ passengers was assaulted on a bus by a co-passenger. The record reflects, however, that in 1988 a bus driver was assaulted by a knife-wielding passenger and in 1986 a bus driver was repeatedly stabbed by a passenger. The shooting at issue in this case occurred in June 1989. Simply because the previous incidents involved knives instead of a gun and drivers instead of passengers does not establish, as a matter of law, that the previous incidents are not substantially similar. Certainly, the criminal attack of a driver with a weapon while he is driving a bus places all the passengers on board at risk from the criminal act. “Whether a ‘substantial similarity’ exists must be determined by the facts of each individual case. It is not required that the offenses be identical. ‘All that is required is that the prior (incident) be sufficient to attract the [defendant’s] attention to the dangerous condition which resulted in the litigated (incident).’ Pembrook Mgt. v. Cossaboon, 157 Ga. App. 675, 677 (278 SE2d 100) (1981).” MARTA v. Allen, 188 Ga. App. at 903. We cannot hold as a matter of law that a jury could not find from the evidence that the previous assaults were sufficient to alert defendants to the dangerous condition or threat posed by passengers carrying weapons onto buses and that defendants failed to exercise extraordinary care to guard against such danger. Thus, the trial court erred in granting summary judgment to defendants.
Plaintiffs also argue that a jury could find defendants failed to exercise the appropriate standard of care under the circumstances because defendants failed to follow their own safety rules. We agree. Defendant Travel, Inc. acted as the agent for Southeastern Stages, Inc. in managing the Augusta bus terminal at which the co-passenger assailant bought a ticket and boarded the bus. Travel, Inc.’s employee manual contains the rule that “[a] 11 accidents and unusual occurrences, however trivial they may seem at the time, involving customers, employees, or other persons, must be reported immediately to a supervisor of the company.” The evidence, when viewed in the light most favorable to the non-moving party, shows that the assailant told the agent who sold him a ticket that there “probably would be an undercover cop . . . looking for him” and instructed the agent “to tell them that he hadn’t seen him.” Later, the assailant reminded the agent not to “forget what I told you.” The record contains the testimony of the ticket agent who stated he thought nothing of the statement at the time it was made and did not report it to a supervisor. A newspaper reporter who prepared an article about the event, however, *225testified the ticket agent told her about the customer’s statements and when she asked the ticket agent what he thought of the shooting, he responded, “I bet you that’s him.” In his deposition testimony, the agent referred to the customer’s statements as “unusual.” Plaintiffs argue the evidence thus creates an issue for jury determination concerning whether the agent violated the company’s rule requiring employees to report unusual occurrences to a supervisor and thus breached a duty to the victim.
“Privately established ‘rules are admissible as illustrative of negligence, but the violation of such a rule is not negligence in and of itself. [Cits.]’ [Cit.]” Luckie v. Piggly-Wiggly Southern, 173 Ga. App. 177, 178 (325 SE2d 844) (1984). Private guidelines are admissible and relevant to show what constitutes the exercise of the appropriate standard of care in a specific situation. Id. Thus, we agree with plaintiffs that a jury could find defendants violated their own private guidelines in this case and from this finding could conclude defendants failed to exercise the appropriate standard of care owed to the victim in this case.
Finally, plaintiffs assert that the behavior of the assailant, in making the unusual remarks to the ticket agent, creates an issue for jury determination concerning whether defendants knew, or in the exercise of extraordinary care should have known, that the assailant posed an unreasonable risk of harm to the victim. In their motion for summary judgment, defendants relied upon cases from the earlier half of this century which held that even the intoxication of a passenger, who was not otherwise behaving boisterously, was not sufficient to alert a carrier that the passenger posed an unreasonable threat of harm to fellow passengers. Compare, e.g., Pinnell v. Yellow Cab Co., 77 Ga. App. 73 (2) (47 SE2d 774) (1948) and Powell v. Beasley, 57 Ga. App. 231 (194 SE 926) (1938) (in which the passenger’s mere intoxication was insufficient to put defendant common carrier on notice that the passenger posed a threat to the safety of other passengers) with Hillman v. Georgia R. & Banking Co., 126 Ga. 814 (56 SE 68) (1906) and Grimsley v. Atlantic Coast Line R. Co., 1 Ga. App. 557 (1) (57 SE 943) (1907) (in which an intoxicated passenger’s boisterous behavior created an issue for jury determination concerning whether the defendant common carrier should have known the passenger posed a threat to the safety of other passengers). From these cases, defendants argued the evidence of the assailant’s odd statements is insufficient to show they breached the duty of extraordinary care owed to the victim because the assailant was neither intoxicated nor behaved in a violent manner.
Before a common carrier may be liable for injury from a criminal assault by another passenger, the carrier must have “ ‘[knowledge of the passenger’s danger or of facts and circumstances from which that *226danger may reasonably be inferred. . . .’ ” Savannah, Fla. & W. R. Co. v. Boyle, 115 Ga. 836, 839 (42 SE 242) (1902). Yet, our analysis in this case must go beyond whether the assailant displayed boisterous behavior which would have provided notice to defendants that the assailant posed a threat of harm to other passengers. A jury may determine from the evidence of previous violent attacks with weapons on board defendants’ buses that defendants failed to exercise extraordinary diligence in conducting only a visual inspection of the assailant for weapons in this case. A jury may determine from the defendants’ own rules, which are relevant to the issue of the standard of care owed in a particular situation, that the standard of care owed to the victim in this case was greater than that imposed by those older cases, cited above, which relieved a common carrier of liability if the carrier was not alerted to the risk of harm to fellow passengers by a passenger’s display of boisterous behavior. A jury may conclude that the customer’s statements supplied defendants with the facts and circumstances from which a danger to other passengers could have been discovered had the defendants followed their own rules.
The duty imposed upon a common carrier for the safety of passengers is that of extraordinary diligence. OCGA § 46-9-132. A jury may, indeed, conclude, as defendants argue, that the customer’s statements were so vague as not to arouse in the extraordinarily diligent mind the knowledge that the customer was potentially dangerous to other passengers. On the other hand, hostage-taking, mass murder and other anti-social behavior in public places is regretfully not uncommon in this time. In light of the evidence of previous attacks by passengers carrying deadly weapons onto the bus, we cannot conclude as a matter of law that a jury could not find that the customer’s statements were so “unusual” so as to require, pursuant to defendants’ rules, a report to a supervisor who, in the exercise of extraordinary diligence would have discovered that the customer was armed. Thus, the trial court erred in granting defendants summary judgment.
Judgment reversed. McMurray, P. J., Cooper and Johnson, JJ., concur. Beasley, J., concurs in judgment only. Sognier, C. J., Birdsong, P. J., Carley, P. J., and Andrews, J., dissent.