U.S. Air Force Tech. Sgt. James Gardner, 633rd Security Forces Squadron assistant flight chief, checks on injured Airmen 1st Class Matthew Equid, 633rd Logistics Readiness Squadron material management apprentice, and Mark Reposar, 1st Operations Support Squadron air traffic control apprentice, during an active shooter exercise at Langley Air Force Base, Va., Dec. 8, 2011. The exercise allowed Langley AFB to test and evaluate first responders faced with multifaceted events affecting the installation. (U.S. Air Force photo by Airman 1st Class Kayla Newman/Released)