NORMAN, Okla. (KFOR) – 911 calls of an active shooter on the University of Oklahoma’s campus flooded Norman dispatch in April.

According to OU Campus Safety‘s Twitter account on April 7, OU- Norman Emergency tweeted, “there is an active shooter at the Van Vleet Oval. Take immediate action now. Run, Hide. Fight!”.

The first call that came into Norman dispatch about the situation was from an alleged father who claimed his son was planning a shooting on OU’s Norman campus.

“Hello. I just got home from work and my son left me a note here saying ‘Dad I love you, but I have to go to the University and shoot everybody.’ All my guns are gone and everything is just left messy in my house,” the caller said.

Another call came in shortly after from someone claiming to be on OU’s campus that night.

“We’re sitting here in the South Oval on Norman campuses and someone is running around with an AR-15 here,” said the person.

The dispatcher on the other end asked for a description of the alleged shooter.

“He’s a white man. He’s 6 foot tall. Around 6 foot tall. Black coat and an AR-15,” the person replied.

What appeared to be gunshots then go off in the background.

“Shots fired, shots fired!,” yelled the dispatcher.

The dispatcher asks if anyone had been shot.

“Yeah. My friend is hit,” said the caller. “One in the stomach and one in the leg.”

Another round of gunshots goes off, sending OU’s campus into a lock down.

Norman dispatch was then flooded with dozens of calls from terrified parents, students and faculty in hiding, and people claiming to see a “person of interest.”

“I am not in Norman but I’m calling to give you information. I understand that there is an active shooter on the campus of OU right now. I know because my daughter has texted me. She is in hiding with several of her friends,” a frantic dad said on a 911 call.

An apparent OU student saying, “Can you call police and get send someone to get me back to my dorm? There’s an active shooter.”

With every phone call, dispatchers remained calm in telling callers to stay safe, lock the doors, and to call back immediately if they’re in danger.

“I got a phone call from my friend’s mom. There’s 100 people on the Norman campus in the ballet theater in the basement,” stated another caller.

University of Oklahoma Police Department Chief Nate Tarver previously told KFOR well over 100 emergency responders from different agencies rushed to secure campus.

As alarmed students took shelter campus wide, a fleet of agencies, including the Cleveland County Sheriff’s Office and the Oklahoma Highway Patrol, searched for an active shooter.

Body camera video released by Norman Police Friday afternoon showed law enforcement looking through dumpsters, in alley ways, and through windows.

Just over an hour later, the ‘All Clear’ was given.

Officials believe the initial 911 calls sounding the alarm about an active shooter were “swatting.”

Law enforcement also believes the phone calls came in from outside the United States.

Norman Police told KFOR the investigation has been taken over by the Federal Bureau of Investigation Friday afternoon.