Doug Stanglin

USA TODAY

A report of gunfire at the University of Oklahoma prompted a campus lockdown Wednesday, but apparently was a false alarm, OU President David Boren said

"At this time, there is no evidence that shots were fired," Boren told reporters.

He said the sound of a gunshot could have been machinery backfire at a construction site on campus, The Oklahoma Daily reports.

Officials lifted a campus-wide shelter-in-place order except at Gould Hall, where the initial report of gunfire was centered.

"Classes are going on as normal in all other buildings except Gould Hall," Boren said. "Additional search of Gould Hall is being conducted just in case. It appears to have been a false alarm."

Police went room to room into the afternoon at the building that houses the College of Architecture.

The initial warning on the OU website reported a "Shooting on campus" and called on students to avoid Gould Hall, the architecture building, and to shelter in place. The building is located on the south end of campus near the football stadium.

Freshman Brianna Cantu told The Oklahoma Daily that she saw motorcycles driving up the South Oval as police told students to clear the area.

"We saw police get off their motorcycles, and one pulled out a gun," Cantu said. "It wasn't even a regular gun it was like a freaking rifle."

The university, located in Norman, has an enrollment of around 31,000 students.