The State Department of Corrections is joining the Corrections Corporation of America in looking into what sparked the brawl at CCA's Cimarron Correctional Facility in Cushing.

The prison is still on lockdown, in order to let people cool down and to avoid further confrontation. Also, it makes it easier for investigators to sweep for weapons, do interviews, and get a handle on what happened.

It was around 4:36 Wednesday afternoon, when CCA officials said staff at the Cimarron Correctional Facility responded to fighting in three separate units. By 5:15 p.m. the incident was over.

“Our staff did an excellent job in responding quickly in bringing this incident, quelling this incident very quickly with no injuries to staff and no threat to public safety,” said Steve Owen with the Corrections Corporation of America in Nashville.

Ambulances transported 11 prisoners to local hospitals with non-life threatening injuries, five remain hospitalized Thursday.

Now, the question is how did this happen.

Some have been warning for years that riots were inevitable at Oklahoma prisons.

“We're at the point where it's not a matter of if, it's a matter of when,” said Corrections Officers William Weldon in 2012 interview.

In 2012, a group of corrections officers told News 9 understaffing, due to low pay, was a riot risk factor.

In 2015, DOC facilities are not only understaffed, News 9 saw they're also overcrowded, which adds to the risk.

“Well, it makes it just a little bit more stressful on offenders," said Warden Jim Farris of the Lexington Assessment and Reception Center. "When you get more people and you compact them into a small area, naturally the tension rises.”

But unlike state facilities, Cimarron is a private prison, pay is better, and understaffing is not as much of an issue

“I'm not aware of any indication that staffing levels played a role or a factor in what occurred yesterday,” said Owen.

But what may well have played a role, considering that the fighting took place in three different units, is the possibility that it was a coordinated assault.

“That's always a possibility,” continued Owen.

CCA officials say questions like that will be answered by the joint investigation.

DOC officials say it's been ten years since they've had an incident of this magnitude. There was a bad riot in 2011, also at a CCA facility, North Fork Correctional Facility in Sayre but that involved California inmates.