The mutiny broke out late yesterday during weekly visiting hours at the jail in the northern city of Buraydah, the prisons authority spokesman told the official SPA news agency.
"Three administrational offices at the prison were torched during the riots caused by some inmates," said the official.
"Security forces at the site managed to control the situation" and put out the fire, but two policemen and two prisoners had been hurt and hospitalised, he added.
Buraydah is the capital of Qassim province, a stronghold of radical Islam in the ultra-conservative kingdom.
But according to informed sources, the jail where the mutiny broke out only holds prisoners convicted for criminal offences.