At least 21 prisoners were killed after a fire broke out during a pre-dawn prison uprising, judicial officials have said.
Unconfirmed media reports said the victims were burned to death in the riot in the Reynosa prison in Tamaulipas state in the northeast, which holds about 2,000 inmates.
An official with the state's Chief Prosecutor's Office told AFP the uprising had been brought under control and that 21 bodies were found when authorities checked the premises.
"We don't know the reasons behind the uprising, during which some inmates set a building on fire where other prisoners were housed," warden Apolonio Villarreal Soto told reporters yesterday.
The official said one wing of the Reynosa prison was notorious for housing inmates "armed even with hand grenades.