Washington Navy Yard on lockdown amid reports of shooter

The Navy Yard in Washington was put on lockdown Thursday amid unconfirmed reports of an active gunman on the military facility, the scene of a deadly shooting two years ago, the US Navy said.

The lockdown comes amid security jitters as the United States prepares for the July 4 Independence Day holiday, with major festivities planned in the capital.

A Navy officer who was inside the complex told CNN people scrambled for cover after hearing someone shout to get out of their building and stay away from the cafeteria.

But Lieutenant Commander Scott Williams said he heard no shots or saw any signs of a struggle.

"We heard someone scream, get out of the building, stay away from the cafeteria and we saw everyone running for the exits or adjoining offices," he said.

The Navy, which told people at the site to shelter in place, said on Twitter that no "incident can be confirmed as of yet."

"#NavyYard lockdown/shelter continues. No further info at this time. More to follow," it said.

Television images showed people emerging from the complex with their hands in the air, which workers said was part of their standard evacuation drill.

Police cars converged on the scene in southeast Washington, and a huge traffic jam formed outside the complex as two helicopters and a fixed wing aircraft circled overhead.
A couple of dozen troops in fatigues were seen massing on a nearby soccer field.

Authorities meanwhile stepped up security outside the White House, closing the pedestrian mall that runs along Pennsylvania Avenue and the adjoining Lafayette Square.

The Navy Yard was the scene of a September 2013 shooting that saw a lone gunman fatally shoot 12 people before being killed himself in a shootout with police.

The complex houses Navy offices and is the headquarters for a number of naval operations.

The United States is on heightened alert ahead of the July 4 national holiday.

The FBI, Department of Homeland Security and National Counterterrorism Center have warned the public of an increased risk of attack during the long Independence Day weekend.