U.S. Air Force Senior Airman Ryan Woody, 633rd Civil Engineer Squadron emergency management flight, uses the Ahura FirstDefender system to test unidentified substances during the HAZMAT portion of an active shooter exercise at Langley Air Force Base, Va., Dec. 8, 2011. The exercise helped to prepare 633rd Air Base Wing personnel for future exercises and potential real-world situations. (U.S. Air Force photo by Airman 1st Class Kayla Newman/Released)