In a span of 40 minutes, a violent riot stirred in Topo Chico prison, located in the northeastern Mexican city of Monterrey, resulting in a brutal massacre killing 40 people, and leaving 5 out of the 12 injured in critical condition. Out of the 40 people killed, one inmate died from shooting, and the rest were killed from a combination of other weapons such as knives and bottles.

The initial sign of the battle began when inmates started creating fires by lighting furniture and chairs, filling the air with smoke.

“Fighting broke out before midnight in two areas of the Topo Chico prison between supporters of a gang leader known as 'Zeta 27' and another group, [led by Jorge Ivan Hernandez Cantu, who has been identified by Mexican media as a Gulf cartel figure] with prisoners using bottles and blades,” Neuvo Leon state Governor Jaime Rodriguez said. As mayor of the city of Monterey, Rodriguez has survived two assassination attacks while advocating against the drug cartel.

Back in 2012, 44 inmates, who were identified as members of the infamous Zeta gang, died in an attempt to escape Nuevo Leon prison.

Many worried family members stood outside the gate of Topo Chico prison.

“The problem is they have people like my brother living with narcos,” an angry relative of an inmate doing time for robbery said to Reuters.

“I want to know that my daughter is okay. She is in the infirmary. There are children in there,” one woman told Telesur News, as she stood outside the prison along with other relatives.

According to a 2014 report by the National Human Rights Commission, “Topo Chico was designed to house 3,685 prisoners but actually held about 4, 585 that year.”

A 2014 human rights report blames Topo Chico for not preventing the devastating result of violence. The prison was known for extreme violence as they took in members of the Zetas. Furthermore, one of the Zetas leader was stabbed to death back in September.

In order to decrease the overpopulation in Topo Chico prison, authorities are in the process of transferring 60 inmates.

This outburst is marked as one of the deadliest riots that occurred in the crowded prisons and among the heavy drug cartels in recent years.