CRANSTON, R.I. (WPRI) — A fight between two inmates at the Maximum Security facility at the ACI in Cranston Friday night leading to a lockdown, remains under investigation.

“An inmate jumped another inmate … broke his jaw but knocked him out,” said 12 News Law Enforcement Analyst Steven O’Donnell, who is a former corrections officer and served for more than five years as Rhode Island State Police’s superintendent.

Ryan Crowley, a spokesperson for the Rhode Island Department of Corrections, said the incident began around 7 p.m.

The fight prompted a response from officers and one correctional officer ended up suffering minor injuries. That officer was treated on scene before seeking treatment offsite and being released.

Department staff responded immediately and were assisted by emergency personnel who did not enter the facility at any time.

“To bring in CERT teams, SWAT teams, it’s very very unusual,” O’Donnell said. “It’s very rare. You can tell by the response. This place was packed with law enforcement last night, so corrections felt it was bigger than the typical disturbance that happens in the prison.”

O’Donnell also made clear that Friday night’s incident at the ACI was not a riot.

“They weren’t disruptive in the sense that they were breaking things, they weren’t burning things and they weren’t assaulting each other. If one of those things happened, the corrections officers and the state police and the local police that were there would have to make some type of decision to use force,” O’Donnell stated.

After the altercation, several dozen inmates refused to return from the secure yard to the inside of the Maximum Security facility.

Correctional officers subdued the situation by engaging with the inmates who refused to go back inside.

Officers accounted for each inmate in the secure yard as they voluntarily returned to the inside of Maximum Security without further incident.

A 12 News crew said the scene began to clear after 2 a.m. The matter remains under investigation.

“I would be surprised if the 60 [inmates] involved are not in a lockdown status in their cell until they can investigate it,” O’Donnell said.