52 dead in riot at Mexico's prison

A prison riot in northern Mexico overnight that left dozens dead started as a fight between leaders of rival gangs, officials said Thursday.Fifty-two people were killed inside Topo Chico prison in Monterrey, Mexico, Nuevo Leon state Gov. Jaime Rodriguez said at a news conference.Twelve others were injured, including five in critical condition, he said. Inmates set fires during the riot, which affected two of the prison's units, the governor said.Local news outlets showed video of flames rising from the prison.The riot started half an hour before midnight and was under control by 1:30 a.m. (2:30 a.m. ET) Thursday, Rodriguez said.State and federal forces as well asrelatives of inmates amassed outside the site Thursday.Mexico has seen deadly riots and other prison violence in the past.At the same prison in Monterrey, three inmates were stabbed to death in February 2012.That same month, 44 inmates were killed and 30 escaped in a riot at a prison in Apodaca, near Monterrey. Security officials blamed the violence on a fierce rivalry between drug cartels insidethat prison.In 2011, the head of security at theTopo Chico prison was found dead and mutilated. Authorities at the time said that a note, presumably from a drug cartel, was left with the body.