Five inmates at Avenal State Prison were injured Tuesday when three consecutive riots broke out, a prison official said.
The first riot began shortly before 7 p.m. in one housing unit, soon followed by disturbances in two other housing units, prison spokesman Ed Borla said.
About 50 prisoners were involved. All of them have been placed on lockdown, Borla said.
Prison employees quickly brought the riots under control and no employees were injured, Borla said The injured inmates were taken to area hospitals for treatment. All were returned to the prison.
Borla said three handmade weapons were found; he declined to describe them. The cause of the riots is under investigation