SAN DIEGO — A riot at Richard J. Donovan Correctional Facility - also known as Donovan Prison - left at least six people injured Friday, according to Cal Fire San Diego which was responding to the incident. The agency reported two of the injuries were serious.

Paramedics responded to the prison, located at 480 Alta Road, about 9 p.m. for a fight that erupted in the prison yard involving nearly 100 inmates, according to Cal Fire.

Cal Fire sent eight ground ambulances and two air ambulances to the scene. An update from the agency just before 10:30 p.m. indicated that all six patients had been transported from the scene and taken to hospitals. 

Paramedics remained at the prison until officials confirmed there were no more patients.

The injuries included puncture wounds, cuts and bruises to head, neck
and upper body areas. No staff members were injured, the CDCR said. The
conditions of the injured prisoners were unknown.

RELATED: Ten inmates hospitalized after riot at Donovan State Prison

The California Department of Corrections and Rehabilitation offered the following statement on the incident indicating four inmates were injured, though Cal Fire reported there were six: 

"Officials are investigating a brief riot that occurred at approximately 8:30 p.m. today on Facility A recreation yard at R.J. Donovan State Prison in San Diego.

The incident began when several inmates began fighting on the yard. Responding staff immediately gave participants of the riot multiple orders to stop fighting.

Officers used several rounds of less than lethal use of force methods to quell the disturbance.

Four inmates sustained injuries that required transportation to outside hospitals for treatment. Those injuries included puncture wounds, cuts and bruises to head, neck, and torso areas. Further information on the medical condition of the inmates is unknown.

No staff members were reported injured in the riot."

The riot is being investigated by the Investigative Services Unit at the prison. The Office of the Inspector General was notified and visiting at Facility A has been canceled for Saturday and Sunday. 

Friday's incident marked the third riot at the facility since late last year. In February, 10 inmates were injured, one seriously, in a riot involving 50 prisoners and in December 2018, two inmates were stabbed in a riot that was broken up by prison guards using pepper spray.

Details of what sparked the riot were not immediately available.