2013-09-16T141405Z_1387433631_GM1E99G1PNC01_RTRMADP_3_USA-NAVY-SHOOTING

A police helicopter is seen as police walk on the roof of a building as they respond to a shooting at the Washington Navy Yard, in Washington September 16, 2013. A gunman shot five people at the U.S. Navy Yard on Monday, including two law enforcement officers, and the shooter was being sought in a building housing the Naval Sea Systems Command headquarters, officials said. (REUTERS/Joshua Roberts)