U.S. Air Force Tech. Sgt. Timothy Davidson, foreground, and Senior Airman Stephen Gillum, patrolmen assigned to the 379th Expeditionary Security Forces Squadron, take part in an active shooter exercise conducted at Al Udeid Air Base, Qatar, Aug. 31, 2017. The active shooter exercise tested the knowledge and capabilities of emergency responders and service members across the base. (U.S. Air National Guard photo by Tech. Sgt. Bradly A. Schneider/Released)