Police have given the all-clear for an area of the University of Arizona campus that was searched following a report of a gunman.
The campus police department said officers found no indication of a shooter.
The department tweeted: "UAPD has cleared the Admin Bldg. No one was found, no injuries or signs of a shooting. The Stu Union IS OPEN."
Campus police spokesman Sgt Juan Alvarez said earlier that police received a 911 call about a man with a rifle at the administration building, and numerous officers responded.
Police searched for a few hours before declaring the area open.