Analysis of the Columbine High School massacre and other incidents where law enforcement officers waited for backup has resulted in changed recommendations regarding what victims , bystanders , and law enforcement officers should do . Average response time by law enforcement to a mass shooting is typically much longer than the time the shooter is engaged in killing . While immediate action may be extremely dangerous , it may save lives which would be lost if victims and bystanders involved in the situation remain passive , or law enforcement response is delayed until overwhelming force can be deployed . It is recommended that victims and bystanders involved in the incident take active steps to flee , hide , or fight the shooter and that law enforcement officers present or first arriving at the scene attempt immediately to engage the shooter . In many instances , immediate action by victims , bystanders , or law enforcement officers has saved lives
Columbine High School massacre
Columbine High School massacre
Mass murder