Stay tuned for more updates.

Via NBC:

As many as seven people were shot – two of them police officers – on the grounds of the Washington Navy Yard Monday morning, and the shooter has not yet been apprehended, authorities confirmed.

One of those shot was a D.C. police officer, reported NBC News’ Pete Williams.

The U.S. Navy says three shots were fired at 8:20 a.m. inside Building #197 at the Naval Sea Systems Command Headquarters, 1336 Isaac Hull Ave. in the Southeast section of the District. U.S. military officials say the gunman – armed with an AR-15, a military-style assault weapon – first shot an U.S. base security officer.

Authorities say a base police officer also was seriously injured.

One victim was reported to be on the roof of a building, reported News4’s Tony Tull.

The shots continued to ring out through the morning, including a volley that Tull reported at about 9:20 a.m.

Benson said the suspect is inside a military building and is armed with a rifle and possibly a shotgun.

Authorities say this a lone gunman.

Update: The left will be devastated it wasn’t a white guy.

Update: Photo of one of the victims.

Update: Four dead, reports are saying 10 people were shot.

Update: Could be the fog of war, but if true this story just took a drastic turn.

Via WaPo:

Update: Starting to sound like a terror attack.

Update: Navy can’t confirm report of multiple shooters.

Update: Still a good chance there was only one attacker, we’ve seen false reports of multiple gunmen in similar shootings only for police to recant later.