U.S. Air Force Staff Sgt. Jarrett Sanders, 633rd Security Forces Squadron Base Defense Operations Center controller, and his team clear the 633rd Civil Engineer Squadron building during an active shooter exercise at Joint Base Langley-Eustis, Va., Dec. 15, 2016. After the active shooter was apprehended, more members of the 633rd SFS, patrolled the building to ensure there were no other threats. (U.S. Air Force photo by Senior Airman Kimberly Nagle)