Rioting prisoners set fire to one block of a low-security prison in southern England early on Saturday and the flames were spreading because fire officers could not approach the building.
The riot at Ford prison near Arundel, West Sussex, broke out around midnight and involved about 40 prisoners who smashed windows and started fires, the BBC reported. Television pictures showed flames rising from the building.
Prison staff were forced to leave and specially trained riot control officers were called in. The fire brigade was on standby but it was not safe to enter the compound, reports said.
There were no immediate reports of injuries, but the fire appeared to be causing serious damage.