LOS ANGELES, Aug. 9 (Xinhua) -- A riot in a large prison in southern California has wounded 250 inmates, among whom 55 were taken to hospitals, prison officials said Sunday.

    The riot, touched off by fighting between black and Hispanic prisoners, broke out Saturday night and lasted 11 hours before it was put down, said Mark Hargrove, spokesman of the California Institution for Men in Chino, about 40 miles (64 km) east of Los Angeles.

    The fighting erupted in one barracks and quickly spread to six others, Hargrove said.

    Prisoners ripped pieces of metal from lockers, destroyed beds and broke off pipes to use them as weapons, Hargrove said. A fire broke out in the chaos, burning down one dormitory, he said.

    No prison employees were injured, no deaths were reported, and no inmates escaped, prison officials said.

    Damage to the 1,300-inmate medium-security prison was "significant and extensive," said Hargrove. One housing unit was virtually destroyed and the other housing areas were so badly damaged that they were uninhabitable, he said.

    By Sunday evening, the barracks were clear. More than 250 inmates suffered injuries, including small cuts, serious stab wounds and head trauma, Hargrove said.

    Of the 55 inmates sent to hospitals, 17 remained hospitalized by Sunday evening, he said.

    The disturbance was the prison's most violent since a December 2006 uprising, in which 200 inmates rioted for 90 minutes. That racially charged incident was touched off by a fight between a Latino and an African-American.

    With more than 150,000 inmates, the California prison system is one of the most crowded in the nation, with many of its facilities holding more than double the number of inmates they were designed for.

    Last week, a panel of three federal judges called conditions " appalling" and ruled that the state must shrink its prison population by nearly 43,000 inmates over the next two years to meet constitutional standards.

    Following a 2005 Supreme Court decision that found automatic segregation to be illegal, Chino and other California prisons are moving away from the historic practice of separating inmates by race.

    Hargrove said inmates could now opt out of segregation and a growing number of black, Latino and white prisoners shared cells, increasing racial tensions in the prison.

    All prisons in southern California were put on lockdown as a result of the riot. Visitation was suspended until further notice.

    On Sunday, investigators still were determining what caused the melee and what sparked the fire.