http://www.theguardian.com/world/2016/feb/11/dozens-killed-in-prison-riot-in-monterrey-mexico?CMP=twt_gu

State governor confirms the death toll Friday morning and tells reporters that the riot at the Topo Chico prison had begun shortly before midnight

A riot at a prison in the Mexican city of Monterrey involving inmates belonging to rival drug cartels has left at least 52 dead and 12 injured, just days before Pope Francis is due to visit another prison in northern Mexico.

Jaime Rodríguez, the governor of Nuevo León state, which encompasses Monterrey, confirmed the death toll on Friday morning and told reporters that the riot at the Topo Chico prison had begun shortly before midnight.

“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”. The leader of the other group, Jorge Iván Hernández, “El Credo”, was identified by Mexican media as a leader of the Gulf Cartel.

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.