At least four people were killed and several wounded in a shooting rampage, involving reportedly multiple shooters inside the Washington Navy Yard, Navy officials reported.
It was first reported that a gunman dressed in all black, described as an adult black male, about six feet tall with a bald head, fired shots, according to D.C. Metropolitan Police Department spokesman Chris Kelly.
However, some reports say that as many as three shooters had been identified, according to Los Angeles Times.
A Navy spokesperson, Lt. Courtney Hilson, said the number of victims was still preliminary as authorities cleared the Naval Sea Systems Command headquarters room by room.
The shooting occurred at 8:20 a.m., and the "active shooter" remained inside the building at large, the Navy reported.
Emergency personnel, the FBI, U.S. Capitol Police and local D.C. police responded to the shooting, shutting down the nearby traffic and grounding the air traffic at the nearby Ronald Reagan National Airport.
About 3,000 people, both civilians and military, work at the Naval Sea Systems Command Headquarters.