(RNN) - The U.S. Capitol and visitors center were temporarily placed on lockdown Tuesday.
Three suspects were arrested, according to the Associated Press. A person riding in a vehicle fired a machine gun at officers in a tunnel near the National Mall, the AP reported.
The gun was dropped in the tunnel and police eventually pulled the vehicle over two blocks from the Capitol, arresting two suspects on the spot.
A third suspect fled, prompting the lockdown. That suspect was eventually captured and the lockdown was lifted.
The AP reported officers found a large amount of ammunition in the vehicle.
It's the second time in less than a week the Capitol has been placed on lockdown.