Some 40 prisoners have been taken to hospital following a riot and a fire at a jail in the US state of California, according to US media reports, BBC reported.
The violence reportedly broke out on Saturday at the California Institute for Men in the town of Chino, east of Los Angeles.
A prison spokesman told KTLA-TV that the situation had been brought under control on Sunday morning.
He said some of the prisoners' injuries were considered life-threatening.
No prison staff had been hurt, the spokesman said.
The Los Angeles Times newspaper reported that the riot had begun at about 2020 local time (0320 GMT) in one of the prison's seven housing units.
Firefighters attended the scene after at least one of the units caught fire.