Authorities say a brawl involving about a dozen inmates at a Southern California prison sent four men to the hospital with stab wounds.
California Department of Corrections spokesman Luis Patino said Sunday night that the California Rehabilitation Center in Norco will remain on lockdown until the investigation is complete.
Patino said the fight broke out among 10 to 15 inmates in a prison dorm Sunday morning and was quickly quelled.
He says the four injured are in serious condition but expected to survive.
Several other inmates at the center _ which holds about 5,000 inmates in Riverside County _ had scrapes, cuts and bruises and were treated at the prison.