Prison head, guards under investigation APODACA, Mexico, Feb. 20 (UPI) -- Officials say they are questioning 18 guards and the director of a Mexican prison where drug cartel fighting killed 44 people and led to rioting and a breakout. Nuevo Leon Gov. Rodrigo Medina said 30 inmates escaped from the facility in Apodaca, near Monterrey, Nuevo Leon, in northern Mexico, during Sunday's violence between the Zetas and Gulf cartels, CNN reported Monday. The guards and prison director, under investigation, have been relieved of duty. Authorities have offered a 10 million peso ($785,000) reward for information about the missing inmates whom they say they believe to be members of the Zetas. Nuevo Leon state public security spokesman Jorge Domene Zambrano told the Mexican newspaper El Universal 750 inmates from one cellblock invaded another cellblock of 750. Sunday and lasted several hours before state and federal police regained control, Domene told The New York Times. The prison was built to house about 1,700 inmates but held an estimated 2,700, he told the Journal. Nuevo Leon authorities have asked Mexico's Interior Ministry to transfer inmates connected with federal offenses out of the prison, ostensibly to focus more fully and put the hammer down on organized crime, Medina said. The Zetas and Gulf cartels, once part of the same organization, are normally securely separated, he said. The latest outbreak of violence was the deadliest in a series of prison riots in northeastern Mexico, including one last month in the Gulf Coast city of Altamira in Tamaulipas in which 31 prisoners were killed and another in the Tamaulipas city of Matamoros, across the border from Brownsville, Texas, in October that killed 20. The latest riot came four days after a fire at an overcrowded penitentiary in Comayagua, Honduras, killed at least 382 people, making it the world's deadliest prison fire.