UPDATE: No Motive Known in Shooting 9/16/13
WASHINGTON - Investigators haven't determined a motive for today's shooting rampage that left 12 people dead at the Washington Navy Yard, a heavily-secured military installation in the heart of the nation's capital.
As for whether it may have been a terrorist attack, Mayor Vincent Gray says, "We don't have any reason to think that at this stage."
The FBI is in charge of the investigation.
The area that was targeted is part of the headquarters for the Naval Sea Systems Command. About 3,000 people work at the headquarters, many of them civilians.