Riot Breaks Out at San Quentin 4 hospitalized with stab wounds; cause unknown By Matt Cantor, Newser User Posted May 23, 2011 5:39 AM CDT 8 comments Comments In this April 30, 2002 file photo, the Golden Gate Ferry Del Norte passes by San Quentin prison in San Quentin, Calif. (AP Photo/Eric Risberg) (Newser) – Some 200 inmates rioted at San Quentin prison last night, leaving at least four hospitalized with stab and slash wounds. Others suffered minor injuries. Guards, who fired non-lethal bullets and pepper spray to halt the violence, found at least 10 inmate-made weapons afterward. The cause of the fight, which occurred in the California prison's dining hall, remains unclear, the AP reports. The Marin Independent Journal notes that "various ethnic groups were involved."