A lone gunman was taken into custody Monday afternoon after shots were fired at the U.S. Capitol, causing the complex to be put on temporary lockdown.

Capitol Police Chief Matthew Verderosa said a man pulled out a gun during a routine security screening at the entrance to the Capitol Visitor Center and aimed the weapon at police. Verderosa said officers fired at the man, wounding him. The suspect was taken to a hospital and was undergoing surgery.

The chief said a female bystander suffered what appeared to be minor injuries and was transported a hospital. Congress was in recess Monday for the Easter holiday, but many tourists were taking tours of the Capitol when the shooting took place.

Verderosa said no police officers were hurt in the incident.

"We believe this is the act of a single person," Verderosa said. He said the suspect has visited the Capitol before, and added that there is no reason to believe the incident was anything more than a criminal act. Police did not release the suspect's name.  

While the incident was taking place, people inside the Capitol were told to shelter in place. Police also cordoned off access to the complex. The lockdown order was later lifted.

A lobbyist from California who was at the Capitol, Jill Epstein, told VOA she was at the Visitor Center during a break in between her meetings.

“As we were going through, just at security, at the metal detector, I was with my colleagues. One person had his wallet and his phone still on the conveyor belt, another one had her shoes off, and all of a sudden people start screaming, ‘There is an active shooter, run.’ We didn’t know whether to go in or out, and we just got out.”

She said armed police were suddenly everywhere and told her to crouch down by an outdoor wall.

Capitol Police secure the Capitol Visitor's Center
Capitol Police secure the Capitol Visitor's Center on Capitol Hill in Washington, March 28, 2016, which was closed to tourists after a report of a shooting.

Verderosa said it appears the security screening process at the Capitol worked as it was supposed to. He said his office has not determined how many police officers fired their weapons at the suspect.

During the incident, the Secret Service closed the entrances to the White House as a precautionary measure, although no incident was reported there.

It is a busy week for tourists in Washington. Many of them have come to see the world renowned cherry blossoms that are now in full bloom around the nation's capital.

In 1998, two Capitol Police officers were killed when a man opened fire inside the complex. After that episode, Congress initiated plans for a new visitor center that expanded and improved its security.