A simulated active shooter aims a fake weapon during

A simulated active shooter aims a fake weapon during an Active Shooter Full Scale Exercise at Robert E. Bush Naval Hospital, aboard Marine Corps Air Ground Combat Center Twetynine Palms, Calif., May 16, 2017. The exercise allowed for the naval hospital, Provost Marshals Office, Fire Department and Naval Criminal Investigative Service to practice and assess their ability to detect, identify and respond to an active shooter incident, validating emergency response procedures. (U.S. Marine Corps photo by Cpl. Thomas Mudd)