The origins towards a militarized US police come from the 1997 North Hollywood shootout from Wikipedia. Now there were SWAT teams starting in the 1960s in Philadelphia to deal with bank robberies. However, these expanded into anti-riot squads dealing with the race riots later in the 1960s and 1970s.
The 1997
North Hollywood shootout had a profound effect on law enforcement agencies. Local patrol officers at the time were typically armed with their standard issue
9×19mm or
.38 Special pistols, with some having a
12-gauge shotgun available in their cars. The North Hollywood bank robbers carried fully automatic
AK-47-style weapons with high capacity
drum magazines and ammunition capable of penetrating vehicles and police Kevlar vests. With these weapons, two bank robbers fired approximately 1,100 rounds at officers and civilians before being killed. The robbers wore
body armor which successfully protected them from bullets and shotgun pellets fired by the responding patrolmen. Police noted that the service
pistols carried by the first responding officers had insufficient range and relatively poor accuracy, although a SWAT team eventually arrived with sufficient firepower.[
