Initial reports said a police officer sustained minor injuries, but later reports from Capitol officials indicated there was no injury to any law enforcement officers.

The event unfolded with Congress on recess and lawmakers back in their districts, but the Capitol complex was teeming with spring tourists. The White House was briefly put on lockdown, although that was soon lifted. A notification sent to Senate offices said no further suspects appeared to be at large.

Capitol office buildings and the Capitol itself re-opened for business about an hour after the initial reports of gunfire. The Visitors Center where the shooting occurred remained closed as the incident was being investigated.

Visitors were being turned away from the Capitol as emergency vehicles flooded the street and the plaza on the building’s eastern side. Police, some carrying long guns, cordoned off the streets immediately around the building, which were thick with tourists visiting for spring holidays and the Cherry Blossom Festival.

Cathryn Leff of Temecula, California, in town to lobby with the California Association of Marriage and Family Therapists, said she was going through security at the main entrance to the Capitol Visitors Center when police told people to leave immediately.

Outside, on the plaza just to the east of the Capitol, other officers told those there to “get down behind this wall,” she said. “I heard what sounded like two shots off to my left.” After a while, police told her and others to keep running. “I felt like I was in a movie. It didn’t feel real at all.”

Amanda Smith of Columbus, Ohio, said she and her family were touring the Capitol and were in the Senate visitors’ gallery when she heard police officers’ radios start talking about shots being fired.

“Sure, we were worried,” she said. “But there were lots of kids around so we didn’t make too big a deal of it.”

Smith was visiting with her husband, William, and children Ian, 9, and Evan, 4.

Traffic was jammed in the vicinity, but despite the obvious emergency the scene was relatively calm. A work crew on the north side of the Supreme Court, across the street, was asked to stop work and move away from the building as a precaution.

Capitol Police provided no immediate information but scheduled a press conference for later in the afternoon.

From back home in their districts, many lawmakers got in touch with staff to ensure all were safe, and posted thanks on Twitter as it appeared they were.