A prison riot in northern Mexico left at least 40 people dead early Sunday, according to a security official.
Nuevo Leon state public security spokesman Jorge Domene Zambrano said the riot broke out at about 2 a.m. in a high-security section of a prison in the city of Apodaca outside of the northern industrial city of Monterrey.
A group of inmates in one cell block started to riot and took one of the guards hostage, Domene said. The riot then spread to a second cell block, and at least 40 people died before authorities regained control of the prison a couple of hours later.
Families of the prisoners gathered outside the prison Sunday morning, pushing at the fences and shouting at police to demand word of the victims.
Deadly fights happen periodically in Mexican prisons as gangs and drug cartels stage jail breaks and battle for control of penitentiaries, often with the involvement of officials.
Some 31 prisoners died in January in a prison riot in the Gulf coast city of Altamira in Tamaulipas state, which borders Texas. Another fight in a prison in the Tamaulipas border city of Matamoros in October killed 20 inmates and injured 12.
In July, a riot at a prison in the border city of Juarez killed 17 inmates. Mexican authorities detained the director and four guards over that clash. Surveillance video showed two inmates opening doors to let armed prisoners into a room where the slain victims were reportedly holding a party.
Twenty-three people were killed in a prison riot in Durango city in 2010, and a 2009 riot in Gomez Palacio, another city in the northern Mexican state of Durango, killed 19 people.