Updated

Inmates at a maximum security prison in Southern California jumped guards in the prison yard, sparking a riot that left one inmate dead and at least 30 inmates and 20 guards wounded, officials said.

The riot at Calipatria State Prison (search) near San Diego began Thursday afternoon when a guard was slashed in the head as he tried to search an inmate he suspected of concealing a weapon, said Terry Thornton, spokeswoman for the California Department of Corrections and Rehabilitation.

Prisoners rioted in the yard for about 45 minutes before guards could bring them under control. Another group of inmates then jumped into the yard and attacked the staff about 20 minutes later, said prison spokesman Lt. Ray Madden (search).

Some inmates attempted to breach a control booth by "throwing brooms and shoving sticks in," said Lance Corcoran, executive vice president of the California Correctional Peace Officers Association.

He said a tower guard broke up the rioters by firing his gun.

The inmate who died had been shot in the abdomen, officials said. Five inmates were taken to outside hospitals, while at least 25 inmates were treated at the prison.

Sixteen guards were treated at hospitals and released Thursday night, including the two most seriously wounded. Four others suffered minor injuries.

The prison in Imperial County east of San Diego houses more than 4,000 inmates. Ninety inmates were placed in administrative segregation after the riot, which means they will be locked up for 23 hours a day until they have an administrative hearing, Madden said.

The incident follows a riot at San Quentin Prison (search) on Aug. 8 that left 42 inmates injured. That fight broke out between white and Hispanic inmates in a medium security dormitory-style unit that houses but only last six minutes, officials said.