Dozens of people were killed in a riot and blaze at an overcrowded prison in the northeastern Mexican city of Monterrey early on Thursday, local media reported, days ahead of a planned visit by Pope Francis to another prison in Mexico´s far north.
Milenio TV said up to 60 people were killed and dozens injured in the predawn riot at the Topo Chico prison. It said relatives of prisoners had heard gunshots in the early hours.
Prison director, Gregoria Salazar, told relatives that there was fighting in two areas of the prison and that inmates had burnt mattresses and a food-storage area. She said the death toll was still being investigated.
The incident is the latest in a series of deadly riots in recent years to rock the country’s overpopulated prisons, which often house inmates from different drug gangs.
The Nuevo Leon state government said on Twitter the situation had been brought under control and ruled out a prison break but gave no details on what had happened.
"I want to know that my daughter is okay. She is in the infirmary. There are children in there," said one woman outside the prison as other relatives shouted and cursed.
Salazar said the areas holding women and elderly inmates were calm.
Pope Francis is set to begin his first visit to Mexico as pontiff on Friday. Next week, he will visit a prison in the border city of Ciudad Juarez, which was once one of the most violent cities in the world.
Television images showed police vehicles patrolling the streets near Topo Chico. Relatives of inmates shook the prison gates and tossed rocks at guards and police on the other side.
Milenio reported that inmates' relatives who had been within the prison's premises for conjugal visits had seen inmates with burns.
A 2014 human rights report said the prison was packed with 25 percent more criminals than it could hold, and faulted it for not preventing violent incidents. The prison has long housed members of the vicious Zetas drug gang. One Zetas leader was stabbed to death there in September.
In 2012, at least 44 inmates died in another Nuevo Leon prison when members of the Zetas plotted with prison guards to stage an elaborate escape.
In 2013, at least 13 people were killed and 65 injured in a prison riot, which was blamed on gang violence, in the central Mexican state of San Luis Potosi.
Thursday's riot was a harsh blow to Nuevo Leon, where many were uplifted when Jaime Rodriguez, a blunt, outspoken rancher with a penchant for cowboy hats known as "El Bronco," or "the gruff one," defeated President Enrique Pena Nieto´s ruling party last year to win the governorship.
Rodriguez, a former member of Pena Nieto's Institutional Revolutionary Party (PRI), waged a campaign that capitalized on widespread disaffection with the established parties. He was the first independent candidate to win such a post in modern Mexico.