Helicopter is flying above WTOP Dick Uliano at the scene of the shooting.
Ambulances are moving down M Street to leave the scene, reports WTOP's Dick Uliano.
Helicopters are still circling the scene, says WTOP's JJ Green.
People perched on edge of helicopter are spotters, searching the area, says JJ Green.
On the Beltway, there are a major amount of police, Green says.
Representatives at the Pentagon tell JJ Green this situation is not being taken lightly.
WTOP has reporters covering all angles of this shooting. Stay with us online or tune in to WTOP to hear the latest reports.
WTOP's Alan Etter says that he has a friend who is in "shelter in place." Friend says he saw a female victim laying face down.
Ed Buclatin, CNIC director of public affairs, says via Twitter that 4 persons killed, 8 injured, 1 shooter down.
There is a response from military and police at the scene, according to WTOP's Alan Etter, who has a friend in "shelter in place." His friend has moved locations three times during the incident.
WTOP's Hank Silverberg says officials are looker for other shooters, but no other shooters have been confirmed.
Employees do not know when they will be getting back into the building, says WTOP's Brennan Haselton. When evacuations started, employees filed out and it was very orderly, he says.
WTOP's Dick Uliano is at the location of the scheduled news conference. Stay with this live blog for the latest information once it starts or tune in to WTOP.
A federal law enforcement official tells CBS News that there are breaching operations ongoing at the Navy Yard, which may result in gunfire as doors are being blasted open.
Patricia Ward says she was in the cafeteria when she heard three gunshots and then a series of gunshots. She ran with a group of other people.