No further details were provided.
A police officer and local media said authorities were responding to a report of an active shooter at the facility. Reuters could not immediately verify the report.
"No incident can be confirmed as of yet," the Navy said.
The lockdown comes amid heightened security concerns ahead of the U.S. Independence Day holiday weekend.
The Navy Yard, a military installation in the nation's capital, was the site of a 2013 shooting in which a contractor killed 12 people.
The US Park Police did not immediately respond to a request for comment.
More than eight blocks of nearby roads were shutdown as authorities responded to the scene, the Metropolitan Police Department said. — Reuters
