Three inmates were killed in a prison in northern Mexico Tuesday, a security official said. The slain prisoners had entered the Topo Chico prison Monday on kidnapping charges, Nuevo Leon state security spokesman Jorge Domene told CNN affiliate Televisa. Authorities believe the inmates were stabbed to death in targeted attacks, Domene said, according to the state-run Notimex news agency. Two prisoners will be charged with the killings, he said. Initial Mexican media reports described a riot in the prison, located in the industrial city of Monterrey. But later Tuesday, Domene stressed that the situation was different from clashes at another prison in Apodaca, Nuevo Leon, Sunday that left at least 44 people dead. \"Apparently it was a direct attack against these people (in Topo Chico),\" he said, according to Notimex. Thirty inmates escaped after the Sunday riot in Apodaca, about 20 km (12 miles) away, Gov. Rodrigo Medina told reporters Monday. The Apodaca prison\'s director and 18 guards have been removed from their positions and are under investigation, Medina said. Authorities had stepped up surveillance in the area Tuesday, Domene said. From: CNN