Authorities are investigating a report that gunshots were fired near the White House. An AK-47 assault rifle was recovered, officials said.
At least one suspect was still at large and several streets were shut down, NBC Washington reported.
Two cars were seen leaving the area, Secret Service spokesman Edwin Donovan said. The cars were racing on Constitution Avenue toward 17th Street, and one of the vehicles was abandoned at 23rd and Constitution, he said.
Police lost sight of one vehicle but they caught up with a possibly stolen Honda sedan near the Roosevelt Bridge, NBC Washington said. Suspects took off on foot, the station said.
Sgt. David Schlosser of the U.S. Park Police said the agency received a report of shots fired near 16th Street and Constitution Avenue, NW, between the White House and the Washington Monument, at about 9:30 p.m.
He said that shortly afterward, officers located an abandoned vehicle several blocks away on the ramp to the nearby Theodore Roosevelt Bridge.
Donovan said the rifle was recovered but no one is in custody.
Police are looking for bullet holes and haven't confirmed that shots were actually fired. Schlosser said The White House is a fair distance away and doesn't appear to have been the focus.
President Barack Obama was in San Diego, Calif. at the time of the incident on his way to the APEC summit in Honolulu.