Two riots at the Cieneguillas prison in Zacatecas this week have left 17 inmates dead.

At least 60 guards and staff were being investigated after a first clash left 16 dead and five wounded on New Year’s Eve when a second riot occurred Thursday morning, killing another inmate.

Authorities believe that the inmates may have had help from prison staff in smuggling weapons into the facility during family visits on Tuesday.

“The state Attorney General’s Office began an investigation into the 60 guards and the staff working that day with the objective of determining their probable collusion in allowing the entry of weapons,” said Zacatecas Public Security Secretary Ismael Camberos Hernández.

Initial media reports stated that the riot broke out due to a dispute during a friendly soccer game between inmates, but Camberos denied the rumors, stating that the fight was planned by prisoners affiliated with criminal organizations.

At a press conference on Wednesday he said there are inmates affiliated with the Sinaloa, Gulf, Zetas and Talibanes cartels.

He said that preliminary investigations indicate that the violence was begun by members of the Sinaloa Cartel.

Prison staff were alerted to the fight by the sounds of alarms and gunshots during a special New Year’s Eve meal for inmates. It took three hours to get the situation under control.

Four firearms found in the prison after the fight led officials to believe that they were smuggled in on the day of the violence. Prison staff had also confiscated cellular telephones, knives, hammers and drugs on Sunday.

Camberos said the wounded inmates were in stable condition and that others have since been relocated in order to avoid further confrontations.

However, that did not prevent renewed violence on Tuesday when another inmate was killed.

Sources: El Diario MX (sp), Milenio (sp), El Universal (sp)