WASHINGTON (AP) — Police locked down the U.S. Capitol on Friday afternoon after a report of gunshots in the area.

U.S. Capitol Police say all Capitol buildings were being locked down “due to an external security threat” and staff members were told they could not enter or exit the buildings.

A law enforcement official says officers were responding to a report of a possible shooting on a street near the Capitol complex. It wasn’t immediately clear if anyone was injured.

The official could not discuss an ongoing investigation publicly and spoke to The Associated Press on condition of anonymity.