"There is one confirmed injury. Emergency personnel are on scene and a 'shelter in place' order has been issued for Navy Yard personnel," the navy said in a statement.
The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command.
About 3,000 people work at the headquarters, which is responsible for building and buying US warships and combat systems, the navy said.
