Here is an excellent article on why if's necessary for the first responding officer or civilian to immediately engage any active shooter. http://www.policeone.com/active-sho...-single-officer-entry-against-active-killers/ A few high points: 98% of active killers act alone. 80% have long guns, 75% have multiple weapons (about 3 per incident), and they sometimes bring hundreds of extra rounds of ammunition to the shooting site. Despite such heavy armaments and an obsession with murder at close range, they have an average hit rate of less than 50%. They strike stunned, defenseless innocents via surprise ambush. On a level playing field, the typical active killer would be a no-contest against anyone reasonably capable of defending themselves. They absolutely control life and death until they stop at their leisure or are stopped. They do not take hostages, do not negotiate. They generally try to avoid police, do not hide or lie in wait for officers and typically fold quickly upon armed confrontation. 90% commit suicide on-site. Surrender or escape attempts are unlikely. Deaf Wanna kill these ads? We can help!