BREAKING NEWS: Several Killed and up to 10 have been wounded in a shooting at the Washington Navy Yard a Defense Department official has said. 

The official also says that the shooter is 'Contained' but not yet in custody.

Gunshots were reported at 8:20AM at the Naval Sea Systems Command Headquarters building. 

WCVB reported that Rick Mason, a program management analyst who is a civilian with the U.S. Navy, said a gunman was shooting from a fourth floor overlook in the hallway outside his office.

He said the gunman was aiming down at people in the building's cafeteria on the first floor. Mason said he could hear the shots but could not see a gunman.

Shortly after the gunfire, Mason said overhead speakers told workers to seek shelter and later to head for the gates at the complex.

Security has been increase at the Capitol. 

Naval Sea Systems Command is the largest of the Navy's five system commands and accounts for a quarter of the Navy's entire budget. It builds, buys and maintains the Navy's ships and submarines and their combat systems.

Stay tuned for more updates.