Senior Airman Marco Rodriguez, 11th Security Forces Squadron Emergency Services Team operator, stands watch while a room is cleared behind him during an active shooter exercise on Joint Base Andrews, Md., March 9, 2016. EST operators conduct team training twice a month, and base exercises once a quarter, to maintain proficiency. (U.S. Air Force photo by Senior Airman Mariah Haddenham/Released)

11th Security Forces Squadron Emergency Services Team operators perform a three- man stack with a shield man during an active shooter exercise on Joint Base Andrews, Md., March 9, 2016. Conducting exercises like these help law enforcement and emergency response Airmen train, and teach military and civilian employees to stay vigilant of their surroundings. (U.S. Air Force photo by Senior Airman Mariah Haddenham/Released)

Senior Master Sgt. Guy Yesse, Air National Guard Inspector General's Office air inspections division superintendent, simulates an active shooter during an exercise on Joint Base Andrews, Md., March 9, 2016. Exercise programs utilize dynamic interactive scenarios to evaluate proficiency in individual and team responses. (U.S. Air Force photo by Senior Airman Mariah Haddenham/Released)

11th Security Forces Squadron Airmen arrest a simulated active shooter during an exercise on Joint Base Andrews, Md., March 9, 2016. Exercise programs utilize dynamic interactive scenarios to evaluate proficiency in individual and team responses.(U.S. Air Force photo by Senior Airman Mariah Haddenham/Released)

Senior Airman Eddie Jaimes, 11th Security Forces Squadron Emergency Services Team operator, performs rear security with an M-870 shotgun during an active shooter exercise on Joint Base Andrews, Md., March 9, 2016. These exercises utilize dynamic interactive scenarios to evaluate proficiency in individual and team responses.( (U.S. Air Force photo by Senior Airman Mariah Haddenham/Released)

Staff Sgt. Adam Cooper, 11th Security Forces Squadron Emergency Services Team operator, clears a building during an active shooter exercise on Joint Base Andrews, Md., March 9, 2016. These exercises help law enforcement and emergency response Airmen train, and teach military and civilian employees to stay vigilant of their surroundings. (U.S. Air Force photo by Senior Airman Mariah Haddenham/Released)

Airmen from the 11th Security Forces Squadron Emergency Services Team at Joint Base Andrews, Md., clear the Air National Guard Readiness Center during an active shooter exercise March 9, 2016. Conducting exercises like these help test installation personnel on the knowledge, skills, abilities and mindset necessary to successfully respond to an active shooter event. (U.S. Air Force photo by Senior Airman Mariah Haddenham/Released)