A simulated active shooter waits on the first responding 99th Security Forces Squadron Airmen during a base wide exercise at Nellis Air Force Base, Nev., May 12, 2016. On May 9-12, Nellis AFB conducted the exercise to evaluate real-life response capabilities of emergency personnel and the base populace to a variety of scenarios depicting situations that could impact the base at any time. (U.S. Air Force photo by Airman 1st Class Kevin Tanenbaum)