Riot at San Quentin prison involves 200, injures 4

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A view of the California State Prison at San Quentin May 15, 2009 in San Quentin, California.

At least four inmates at San Quentin State Prison were seriously injured Thursday morning when a riot broke out in the exercise yard, according to prison officials.

Prison spokesman Gabe Walters said between 150 and 200 prisoners were involved in the Thursday morning riot. Dozens were slashed and stabbed by fellow prisoners armed with homemade weapons.

Walters says San Quentin guards used chemicals such as pepper spray, projectiles and real bullets to restore order. None of them were injured.

The four most seriously injured inmates were taken to local hospitals. Walters says it's so far unknown if they were hurt by other inmates or by guards.

San Quentin is a maximum security prison that house's California's death row. The exercise yard where the disturbance broke out serves fairly recent arrivals whose security status still is under review.