SACRAMENTO, Calif. — More than a half-dozen inmate weapons were recovered after a riot Friday morning at one of the two state prisons in Folsom, Calif., officials said.

The riot involved about 150 inmates at California State Prison, Sacramento, according to the California Department of Corrections and Rehabilitation.

The weapons included six knives made by inmates and a cane.

At least two inmates at California State Prison, Sacramento, were stabbed multiple times and were taken to an outside hospital for treatment, following the riot at about 10 a.m.

One was in surgery late Friday afternoon and his condition was unknown.

The second suffered a broken eye socket and broken left hand. He was in stable condition.

Two more were taken to the hospital and released back to prison. A final two were still being evaluated for injuries.

Prison officials did not identify any of those involved or their racial or ethnic groups.

The riot took place in the exercise yard of B-Facility, a maximum-security unit in the prison, said LeVance Quinn, a spokesman for the CDCR.

Various groups were involved, but no specifics were available, Quinn said.

Although rival organizations within a prison sometimes spark riots, it was not immediately clear what caused this fight.

Once things get started, inmates may battle out of confusion, Quinn said.

Prison staff quelled the melee with rubber bullets and pepper spray as well as one warning shot fired using a lethal round.

The entire prison is on modified program, or lockdown, during investigation of the riot.

Officials are trying to evaluate recordings from multiple video cameras to determine who started the riot, who actively participated and who merely was caught in the chaos.