Keesler firefighters enter Gerrard Hall in response to a structure fire during a major accident response exercise March 21, 2013, at Keesler Air Force Base, Miss. The scenario involved a leaking propane tank explosion in a supply closet that set the building on fire and injured several airmen. Keesler holds exercises periodically to prepare airmen for real-world emergencies. (U.S. Air Force photo by Kemberly Groue/Released)