A "brief riot" broke out at a Southern California prison Friday night, leaving four inmates injured enough that they were transported to outside hospitals for treatment, the California Department of Corrections and Rehabilitation said.

The riot happened about 8:30 p.m. in a recreation yard at the R.J. Donovan State Prison in San Diego Prison after several prisoners began fighting, the department said.

Officers “used several rounds of less than lethal use of force methods" to stop the violence.

The four inmates were taken to a hospital for injuries that include puncture wounds, cuts and bruises to the head, neck and torso.

The medical condition of those inmates was not immediately known.

No prison staff was reported injured, the corrections department said.

The riot is under investigation.

In February at the facility, 10 prisoners were wounded in a riot with 50 inmates, NBC San Diego reported. In that case, several fights erupted at the same time in the prison's yard for medium-custody inmates, the station reported, and pepper spray was used to stop it.

The Richard J. Donovan Correctional Facility is about 16 miles southeast of downtown San Diego.