WASHINGTON (AP/Reuters) - At least one shooter has been killed following an incident at the United States Navy Yard that left several victims dead and several others injured on Monday, a US Navy official told Reuters.
At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning, and officials said several people were killed and as many as 10 were wounded, including a law enforcement officer.
A federal law enforcement official and a Defence Department official said a shooter had died. Both spoke on condition of anonymity because they were not authorised to discuss the ongoing investigation.
Two other officials have said they were looking into the possibility of a second shooter.
Two US Navy officials say at least six people have died in the shooting, and the Washington police chief said two additional suspects wearing military-style uniforms are at large.
The officials spoke on condition of anonymity on Monday because they were not authorised to discuss the situation publicly.
The Washington police chief said a shooter was killed and a police officer was shot in a gunfight with a shooter.
As many as 10 people were wounded.
Witnesses described a gunman opening fire from the fourth floor, aiming down on people in the first-floor cafeteria. Others said a gunman fired at them in a third-floor hallway.
Schools were on lockdown, and airplanes at nearby Reagan National Airport were briefly grounded. Less than 3.2km away, security was increased at the Capitol, but officials said there was no known threat there.
About 3,000 people work at the Naval Sea Systems Command headquarters, which builds, buys and maintains the Navy's ships and submarines and combat systems.
Mr Todd Brundidge, an executive assistant with Navy Sea Systems Command, said he and other co-workers encountered a gunman in a hallway of their building on the third floor. The gunman was wearing all blue, he said.
"He just turned and started firing," Mr Brundidge said.
Ms Terrie Durham, an executive assistant, said she also saw the gunman firing towards her and Mr Brundridge.
"He aimed high and missed," she said. "He said nothing. As soon as I realised he was shooting, we just said, 'Get out of the building.'"
Mr Rick Mason, a program management analyst who is a civilian with the US 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. Mr Mason said he could hear the shots but could not see a gunman.
Ms Patricia Ward, a logistics management specialist, said she was in the cafeteria and heard shots. They sounded like "pop, pop, pop", she said. After a few seconds, there were more shots.
"Everybody just panicked at first," she said. "It was just people running, running, running."
Ms Ward said security officers started directing people out of the building with guns drawn.
Among the wounded was a D.C. police officer, according to a law enforcement official who spoke on the condition of anonymity because the person was not authorised to discuss an ongoing investigation.
A US Park Police helicopter hovered over the building and appeared to drop a basket with a person onto the roof.
Officials at MedStar Washington Hospital Centre said two shooting victims had been brought there.