At least 52 were killed and 12 have been injured in a riot at Topo Chico prison in the Mexican city of Monterrey involving inmates belonging to rival drug cartels.
Jaime Rodríguez, the Governor of Nuevo Leon State, which encompasses Monterrey, confirmed the death toll,reports Guardian.
'During the clash several prisoners set fire to the food storage and sleeping areas,'Rodríguez said.
It was not immediately clear how the victims died but the Governor said there had been no gunfire.
Rodríguez said that one of the factions involved in the violence was led by a leader of the Zetas cartel, Juan Pedro Saldivar-Farías, known as 'Z-27'.
Los Zetas, founded by a group of former special forces soldiers, were originally the Gulf Cartel's enforcement wing, but turned on their former masters in 2010, triggering a vicious war for territory which has wrought havoc across north-eastern Mexico.