Fighting at a prison in Mexico near the Texas border has left 20 people dead and another 12 wounded.
The violence broke out on Saturday morning after an altercation between two inmates, the government of Tamaulipas state said in a statement.
Guards at the Centro de Ejecucion de Sanciones de Matamoros penitentiary in Matamoro later restored order with the aid of police, the statement added. The Tamaulipas government gave no details of weapons involved or how the victims died.
Many Mexican prisons are overcrowded and often plagued by violence linked to the country's powerful drug cartels. Turf wars between gangs fighting for control of smuggling routes in border regions have been particularly brutal.
The incident in Matamoros was one of the most violent to hit the country's prisons this year.
Since President Felipe Calderon sent in the army at the end of 2006 to try to crush the drug cartels, more than 44,000 people have died in the ensuing violence. REUTERS