250 HURT AS RIOT ERUPTS IN PRISON

As many as 80 officers responded to the riot on Saturday night, which involved 1,300 inmates in seven dormitory-style barracks at the California Institution for Men, in Chino, prison spokesman Lt Mark Hargrove said.

The riot was probably prompted by tensions between black and Hispanic prisoners, Lt Hargrove said.

Officers used pepper spray, wielded batons and shot foam projectiles to remove inmates who had barricaded themselves inside the medium-security facility during the four-hour uprising.

A fire started during the chaos caused significant damage to one of the buildings, Lt Hargrove said.

The inmates' injuries ranged from stab wounds and slashes to head wounds and some of the injuries were considered life-threatening.

No staff members were injured in the disturbance, the largest since December 2006.

All prisons in Southern California were put on lockdown and visitations were suspended because of the riot, officials said.