WASHINGTON (AFP) - A gunman shot and wounded at least one person on Monday in a headquarters building at the US Navy Yard in Washington and is still at large, the navy said.

"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.

Local television reported that there were as many as five casualties, and the navy said that the police had entered building number 197 in search of the shooter.

The navy said at least three shots were fired at 8.20am 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.