A PRISON RIOT in northern Mexico left about 20 people dead earlier today, according to a security official.

Nuevo Leon state public security spokesman Jorge Domene Zambrano told Milenio television that the riot broke out at about 2am at a prison in the city of Apodaca outside of the northern industrial city of Monterrey.

He said authorities at the state prosecutor’s office reported 20 dead. 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.

Authorities regained control of the prison within a couple of hours, he said. Families of the prisoners were gathered outside Sunday morning, seeking 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 Altimara 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.