The White House was on lockdown on Thursday after reported gunfire around the Capitol building.
US Secret Service said that the White House lockdown was a precaution.
The stretch of Pennsylvania Avenue in front of the compound was closed to pedestrians.
Police said that a vehicle tried to ram a barricade at the White House, which started a chase and ended with one officer injured and at least one police car damaged.
Sen. Bob Casey, D-Pa., told reporters he was walking from the Capitol to the Senate Russell Office Building across the street when he noticed several police officers driving fast up Constitution Avenue on motorcycles.
“Within seconds of that,” Casey said, “we heard three, four, five pops,” which he assumed were gunshots. He said police ordered Casey and nearby tourists to crouch behind a car for protection.
In about two minutes, he said, the officers moved everyone into the Capitol.
FBI agents rushed to the scene and Senate Sergeant at Arms Terrance Gainer said: “There are reports of injuries.”
Police are investigating what happened and said they’ll give another update at 4:15 p.m. EDT. A suspect is in custody.
Story developing; check back for updates.
The Associated Press contributed to this report.