A Washington police spokesman said five people had been shot at the Naval Sea Systems Command headquarters, including a District of Columbia police officer and one other law enforcement officer. The Navy did not elaborate.
NBC News, citing a senior naval officer at the Navy Yard, said at least 12 people had been shot, with four killed and eight wounded. This could not be independently confirmed.
A Navy official told Reuters a suspected shooter has been contained, adding that several people died and several others were injured. The total number of victims was unclear, he said on condition of anonymity.
Another Navy official, speaking on condition of anonymity, said more than one shooter may have been involved. The Washington Post reported that there were several shooters.
The Navy said in a statement the shooting took place at the heavily guarded headquarters, where about 3,000 people work.
Dozens of police and emergency vehicles surrounded the complex in southeast Washington, which is about a mile (1.6 kilometers) south of the US Capitol, local media reported.
Helicopters circled the headquarters with some touching down on the building’s roof, according to a live feed by Washington’s WJLA TV.
A Washington police spokesman said the first reports of shots were received at 8:36 am local time.
A White House official said President Barack Obama had been briefed on the shooting. The shooting briefly shut down flights at Reagan National Airport.
The Navy Yard dates to the 18th century and is the oldest Navy installation. It houses a museum, the residence of the chief of naval operations and is responsible for weapons development, among other functions.