Authorities have closed the northbound lanes of a highway in the Washington, D.C., area after a report of a shooting.

The U.S. Park Police issued a statement Monday saying that officers went to the Baltimore–Washington Parkway in the area of Route 410 in response to a report of a shooting. The area is in Maryland just outside of the District of Columbia.

It wasn’t immediately clear if anyone was hit by gunfire.

News stations showed images of traffic backed up on the highway.