Officials say they evacuated the Smithsonian's Hirshhorn Museum and Sculpture Garden when a security guard was found dead of a self-inflicted gunshot wound.

Smithsonian Institution officials say the guard shot himself with his service revolver shortly after 3 p.m. Monday in a locker room in the basement level of the building in the nation's capital.

Officials say no one from the public witnessed the shooting, and no one else was injured. The guard's name has not been released.

The museum on the National Mall was evacuated and will be closed for the rest of the day. The Hirshhorn is the Smithsonian's modern art museum.

Washington, D.C., police are investigating.