A “friendly” soccer match between rival drug cartels at a prison in northern Mexico on New Year’s Eve was anything but, as 16 inmates ended up dead.

Held at the Cieneguillas men’s penitentiary in the state of Zacatecas, the match pitted members of the Gulf and Zetas cartels against one another on the pitch. According to The Daily Mail, an argument about a dirty tackle in the penalty box led to firearms being drawn and shots being fired. A riot followed, and it took the National Guard and prison officials around three hours to put an end to the violence.

In the aftermath of the riot, which also left five inmates wounded, officials discovered four guns which had presumably been smuggled into the prison on New Year’s, when relatives could visit for the last day of the year. Knives were also seized.