Washington police are investigating a supposed shootout near the White House that forced them to close several streets of the capital to traffic, the NBC network said.

Park Police received calls from witnesses shortly after 9 p.m. Friday night saying they heard gunshots and saw two cars speeding west on Constitution Avenue downtown in the nation's capital.

One of the suspected vehicles, a Honda, was found soon afterwards and cops seized an AK-47 assault rifle, but no one was wounded or arrested.

The supposed shootout took place on 16th Street between the White House and the Washington Monument, and forced Constitution Avenue to be closed between 15th and 23rd Streets.

According to preliminary reports, the presidential residence did not seem to have been the suspects' target.

U.S. President Barack Obama and his wife are currently away from the capital on a trip to Hawaii, where they will host the APEC Summit of leaders from Asia and the Pacific.