Master Sgt. Jon Dahlmer, 633rd Security Forces Squadron flight chief of A-flight, communicates with his team after responding to an active shooter during an exercise at Langley Air Force Base, Va., Nov. 15, 2012. Dahlmer said that even during a training exercise, practicing like it’s a real situation is the most effective way to make the right decisions. (U.S. Air Force photo by Staff Sgt. Katie G. Ward / Released)