A huge riot at the Topo Chico prison in Monterrey, Mexico happened on Feb. 10, just before midnight. At least 52 died and 12 were injured in the aftermath.

The Guardian wrote that the riot involved inmates who belonged to rival drug cartels. Jaime Rodriguez, governor of Nuevo Leon state, confirmed the death toll. There was no gunfire, but it is still unclear how the victims died. Thus far, 40 victims have been identified.

“During the clash, several prisoners set fire to the food storage and sleeping areas,” Rodriguez said. There were images of the riot shown on television, with flames originating from the prison. Families of the inmates who discovered the problem on social media immediately gathered around the jail, asking for information about their loved ones and throwing stones at guards.

The governor added that Juan Pedro Saldivar-Farias, also known as “Z-27,” led the Zetas cartel members in the riot. Jorge Ivan Hernandez, also known as “El Credo,” led the Gulf Cartel members.

The fight was managed by authorities at around 1:30 a.m. on Feb. 11. No women or children were hurt, and no inmates escaped from the incident.

According to Reuters, the incident was among the worst in a string of deadly riots that plagued Mexico’s overpopulated prisons in the past few years. Some of the jails are actually controlled by top Mexican drug cartels. The governor also acknowledged the belief of the public that the Zeta drug cartel highly influenced the facility. In 2012, at least 44 prisoners died in another Nuevo Leon prison after Zeta members plotted with prison guards to escape.

Rodriguez said that Topo Chico is a very old prison with very difficult security conditions. He described the prison system in the state as a “time bomb” that had to be defused. The prison has detained Zeta cartel members for many years. The Zetas are well known for their extreme violence. There are about 3,500 prisoners at Topo Chico. Currently, several inmates are set to be transferred out of the prison for decongestion purposes.

The Guardian stated that prison management has been a huge challenge in Mexico as the populations of inmates in various jails continue to grow due to the current attacks on organized crime and drug cartels. Many inmates are compelled to pay high prices for protection and adequate food.

More updates and details on the Topo Chico prison riot are expected soon.