Mexican authorities say a prison riot involving rival drug gangs has left at least 20 inmates dead and several others injured.
The fighting erupted Wednesday at a facility in the northern city of Juarez, which is across the border from the U.S. city of El Paso, Texas. Authorities say inmates from the drug gang "Azteca" managed to free other prisoners who went on a rampage and attacked members of other gangs.
The trouble started as visiting hours ended. Mexican police and military forces were called in to regain control of the prison as helicopters flew overhead.
Juarez is in the state of Chihuahua, where drug-related violence has escalated as gangs vie for trafficking routes into the United States. Thousands of Mexican soldiers are stationed in Juarez to help stop the turf war among the drug cartels who have turned it into Mexico's most violent city.
Mexican officials say they expect more than 7,000 soldiers and federal police in the city by the end of this week.
Mexican President Felipe Calderon has deployed thousands of soldiers to fight drug gangs across the country since taking office in 2006. Despite the effort, more than 6,000 people were killed last year in drug violence.
Some information for this report was provided by AFP, AP and Reuters.