The university first issued the warning just before 10:30 p.m. ET.
“There are active shooters in Van Vleet Oval. Take immediate action now. Run. Hide. Fight!” That university tweeted.
All permits are issued from the campus police department just before midnight ET.
A camera maintained by the university indicates a heavy police presence on the Norman, Oklahoma campus.
NewsNation affiliate KFOR-TV reported that several police agencies responded, including the Oklahoma City Police and Highway Patrol.