WASHINGTON (AP) — Officials say a gunman has been taken into custody after firing shots in the U.S. Capitol complex.

Visitors and staff were shut in their offices and told to “shelter in place.”

Initial reports said a police officer sustained minor injuries, but later reports raised doubts about who, if anyone, was shot.

The event unfolded with Congress on recess and lawmakers back in their districts. The White House was briefly put on lockdown, but that was soon lifted. A notification sent to Senate offices said no further suspects appeared to be at large, and most Capitol Hill buildings were later re-opened for business.

The shooting occurred in the Visitors Center of the sprawling Capitol complex. Staffers, reporters and others were told to “shelter in place” while 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.