Shots have been reported in a building on the Washington Navy Yard campus, an official has said.
Police, the FBI, federal marshals and ambulances swarmed to the scene. Workers on the campus were ordered to stay where they were, and workers who had not reported to work were told to stay home. U.S. military officials said there were reports of gunshots heard, but they said there was no confirmation.
Nearby roads were closed and nearby buildings evacuated. The police response came just before 8 a.m. ET.
On Sept. 16, 2013, Aaron Alexis, a former Navy reservist with a troubled mental health history, opened fire in an office building at the Navy Yard, paralyzing the capital before he was taken out in a gunfight with authorities.
It was the second-deadliest rampage on an American military base, after the Fort Hood shootings in Texas in 2009. The building where Alexis opened fire reopened in February after renovations.
The Navy confirmed the lockdown but could not confirm the nature of the emergency. Dozens of police cars swarmed the site, and a helicopter circled overhead. Department of Homeland Security police directed cars away from the scene.
The Navy Yard is in southeast Washington, near the headquarters of the Transportation Department and the ballpark of the Washington Nationals. It is about two miles from the Capitol.