美国当局：华盛顿海军设施枪击案嫌疑人是单独作案

Authorities in Washington, D.C. say an information technology employee working for a military contractor was the lone suspect in Monday's shooting rampage at a U.S. naval facility that left 13 people dead, including the gunman.

Washington Police Chief Cathy Lanier told reporters hours after the tragedy there was no evidence a second person was involved with Aaron Alexis, a 34-year-old resident of ((the southwestern city/state of)) Fort Worth, Texas, who was killed during a gun battle with police shortly after his shooting spree began.  

Police say Alexis entered the U.S. Naval Yard in the nation's capitol with a valid identification card, armed with a military-style automatic assault rifle, a shotgun and a handgun, and opened fire inside the Naval Sea Systems Command, which is responsible for buying, building and maintaining ships and submarines.  About 3,000 people work in the building, many of them civilians.   

The New York City native served in the U.S. Navy as a reserve sailor from 2007 to 2011.  News outlets say Alexis was arrested in two separate shooting incidents, once in 2004 in Seattle and the second in Fort Worth in 2010.  He has been described as having problems controlling his anger.