Bullet casings rest on the floor as members of the 23d Security Forces Squadron detain the simulated active shooter, Staff Sgt. Christopher Childress, 23d SFS military working dog trainer, during an active shooter exercise, Dec. 8, 2016, at Moody Air Force Base, Ga. This exercise caused included securing entrances to nearly every building on base. (U.S. Air Force photo by Airman 1st Class Daniel Snider)