In Zelig v. County of Los Angeles (2002) 27 Cal.4th 1112, a woman was shot and killed by her ex-husband at a courthouse where she was awaiting a hearing in their dissolution proceedings. Her minor children asserted the county maintained the courthouse in a dangerous condition by failing to install barriers or utilize other safety measures, including metal detectors, posted warnings, and searches. The Supreme Court held that the plaintiffs could not establish a dangerous condition of public property because they were unable to show the necessary causal connection between the physical condition of the property and the shooting. The court emphasized that liability should be imposed "only when there is some defect in the property itself and a causal connection is established between the defect and the injury." (Zelig, supra, 27 Cal.4th at p. 1135.) While in some instances a public entity may be required to alter its property to provide a physical barrier against danger presented by third parties, the Zelig court concluded that the addition of a physical barrier, by itself, would not have had any effect on the risk of harm faced by the decedent or other persons using the courthouse. The court also concluded that other screening methods would have required additional security personnel, which would implicate the provision of police services, an allocation of resources for which public entities are immune. (27 Cal.4th at pp. 1139-1140; 845.) The court continued, limiting that general principle, however, by stating that "past cases establish that police officers . . ., like other persons, generally may not be held liable in damages for failing to take affirmative steps to come to the aid of, or prevent an injury to, another person. 'As a rule, one has no duty to come to the aid of another. A person who has not created a peril is not liable in tort merely for failure to take affirmative action to assist or protect another unless there is some relationship between them which gives rise to a duty to act.' More specifically, 'law enforcement officers, like other members of the public, generally do not have a legal duty to come to the aid of another person . . . ." (Zelig v. County of Los Angeles, supra, 27 Cal.4th at pp. 1128-1129.)