The Columbine High School massacre in Colorado on April 20 , 1999 was another seminal event in SWAT tactics and police response . As the shooters , Eric Harris and Dylan Klebold , were shooting , officers did not intervene in the shooting , but instead set a perimeter as they were trained to do . By the time they did enter the school , 13 people were already killed and Harris and Klebold had committed suicide . As noted in an article in the '' Christian Science Monitor '' , " Instead of being taught to wait for the SWAT team to arrive , street officers are receiving the training and weaponry to take immediate action during incidents that clearly involve suspects ' use of deadly force . " The article further reported that street officers were increasingly being armed with rifles , and issued heavy body armor and ballistic helmets , items traditionally associated with SWAT units . The idea was to train and equip street officers to make a rapid response to so-called active shooter situations . In these situations , it was no longer acceptable to simply set up a perimeter and wait for SWAT . As an example , in the policy and procedure manual of the Minneapolis Police Department , it is stated , " MPD personnel shall remain cognizant of the fact that in many active shooter incidents , innocent lives are lost within the first few minutes of the incident . In some situations , this dictates the need to rapidly assess the situation and act quickly in order to save lives . " According to criminal justice professor Cyndi Banks , the War on Terror , like the War on Drugs , became the context of a significant expansion of SWAT policing . Whereas some have attributed this expansion to " mission creep " and the militarization of police , other scholars argue that increased SWAT policing is a response to real or perceived moral panics associated with fear of crime and terrorism . Banks writes that SWAT team employment of military veterans has influenced their tactics and perspective
Columbine High School massacre
Columbine High School massacre
SWAT