A gunman reportedly opened fire at The Washington Navy Yard this morning, killing at least four and wounding several others. The Associated Press is reporting this morning (via The Washington Post and other outlets) that the Navy yard shooter is “contained,” although not in custody. The media outlet cites a defense official.

washington navy yard shooting

At least 8 injured, 4 killed at Washington Navy Yard

NBC News reports that at least eight people were wounded in at the U.S. Navy yard this morning. The shooting happened at the Naval Sea Systems Command at the Washington Navy Yard. A source told NBC News that at least four people have been killed in the shooting spree and eight others wounded. The source also said that the gunman was wounded as well.

According to officials with the U.S. military, one of those who shot is a naval security guard. They said the guard was shot in both legs. NBC’s Washington affiliate WRC reports that a Washington city police officer had also been shot. At this point it is not clear how many of the other casualties were civilian, police or military.

Navy reports shots fired on Twitter

The initial report of shots fired at the Sea Systems Command headquarters came this morning at 8:20 E.T. from the U.S. Navy, who reported it via Twitter. About an hour after that, the military said the shooter was still “active.” Military officials said the Navy yard shooter might have been armed with a military assault rifle known as an AR-15.

White House security tightened

Right after the shots were reported, officials grounded all flights at Reagan National Airport. Police on Capitol Hill also said they were tightening security on White House grounds. Administration officials said President Obama is getting regular briefings on the situation at the Washington Navy Yard.

According to Navy officials, approximately 3,000 people work at the Navy building where the shootings took place. They were told to remain where they were.