What started as a late-night fight between leaders of rival gangs spiraled into a massive prison riot in northern Mexico that left dozens dead, officials said Thursday.
The riot killed 52 people inside Topo Chico prison in Monterrey, Nuevo Leon state Gov. Jaime Rodriguez said at a news conference.
Twelve others were injured, including five who are in critical condition, he said.
Video showed flames rising from the prison — the result, Rodriguez said, of inmates setting fires inside.
The violent clashes come just one day before Pope Francis arrives in Mexico, a trip that will include a stop at a prison in Ciudad Juarez, a city on the mend after once being known as the murder capital of the world.
Relatives demand answers
The riot started half an hour before midnight and was under control by 1:30 a.m. (2:30 a.m. ET) Thursday, Rodriguez said.
State and federal forces as well as relatives of inmates amassed outside the site. Frantic family members tearfully told CNN affiliate FOROtv that they were worried about loved ones inside.
Images from the CNN affiliate showed people pushing on gates outside the prison. Another group shoved at a line of police officers standing guard near the facility.
“I don’t know if my son is dead!” a woman screamed. “Please, help us. The director should come out and face us, and give us the names. “
“We don’t really know what’s happening,” another woman told reporters. She said her son managed to call her from inside the prison, recounting how once the riot started, he hid for safety in the women’s wing.
Another woman told reporters a similar story — of her son seeking shelter in the women’s wing.
“There is a riot. They want to kill us all. Come ask for me,” the woman said her son told her.
State officials released a list of 20 victims that died in riot, but said investigators were still working to identify others.
The governor called the riot “unfortunate and painful.”
Past riots sprang from cartel rivalries
Mexico has seen deadly riots and other prison violence in the past.
At the same prison in Monterrey, three inmates were stabbed to death in February 2012.
That same month, 44 inmates were killed and 30 escaped in a riot at a prison in Apodaca, near Monterrey. Security officials blamed the violence on a fierce rivalry between drug cartels inside that prison.
In 2011, the head of security at the Topo Chico prison was found dead and mutilated. Authorities said that a note, presumably from a drug cartel, was left with the body.