Fray between rival gangs in a Mexican jail Bring death of 31 prisoners, Reuters reported.
Participants in the battle in the city jail Altamira used knives and home-made weapons. 13 prisoners were injured.
This is yet another outburst of violence in overcrowded prisons in Mexico.
In October brawl at a prison in Tamaulipas state killed 20 prisoners, and in July in such a brawl in the town of Ciudad Juarez killed 17 prisoners.