Four inmates were killed Friday in a fight inside Cereso 1 prison in the northern Mexican city of Durango, an official told Efe.

The trouble broke out around 7:15 a.m. in the cafeteria of Cellblock B, according to Fernando Rios, spokesman for the Durango state Public Safety Office.

The four prisoners stabbed to death in the fight included brothers Guillermo and Humberto Roman Cuevas, whose cousin, Jorge Alberto Cuevas Castañeda, was slain Thursday after he was released from Cereso 1 on parole.

One inmate was killed and two guards injured during a confrontation at Cereso 1 in March.

That incident prompted a search of the prison by federal police, who found assault rifles, handguns and grenades, as well as marijuana.