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 × 19 mm 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 . The ineffectiveness of the standard police patrol pistols and shotguns in penetrating the robbers ' body armor led to a trend in the United States toward arming selected police officers , not just SWAT teams , with heavier firepower such as semi-automatic 5.56 × 45 mm NATO AR-15 type rifles . SWAT teams , whose close quarters battle weaponry usually consisted of submachine guns that fired pistol cartridges such as the Heckler & Koch MP5 , began supplementing them with AR-15 type rifles and carbines
North Hollywood shootout
North Hollywood shootout
Militarization of police