MONTERREY, Mexico (CNN) — Dozens died and 30 inmates escaped during a weekend prison riot in northern Mexico, an official said Monday.

The prison’s director and 18 guards have been removed from their positions and are under investigation, Nuevo Leon Gov. Rodrigo Medina told reporters.

Authorities are offering a reward of 10 million pesos ($785,000) for information leading to the missing prisoners, Medina said. Preliminary reports indicate the escapees were members of the Zetas drug cartel, he said.

A fierce rivalry between drug cartels likely fueled the fighting that killed 44 people Sunday inside the prison in Apodaca, Nuevo Leon, state security spokesman Jorge Domene told reporters.

Prisoners could have used the riot to engineer their breakout, Domene said Sunday. He did not say how prisoners inside acquired the clubs, stones and sharp objects they used in the fighting.

Earlier Sunday, Domene said inmates had taken a guard hostage as clashes broke out at the prison. Some prisoners also set mattresses ablaze, sending a column of smoke rising above the facility, he said.

Federal and state police surrounded the prison as anxious family members awaited information outside its gates.

The clashes, which occurred in a part of the prison where most inmates were serving time for federal drug trafficking offenses, may have begun as a fight between the Zetas and Gulf cartels, Domene said.

The Zetas started with deserters from the Mexican Army and quickly gained a reputation for ruthless violence as the armed branch of Mexico’s Gulf cartel. The partnership ended in 2010, and turf battles between the rival cartels are common in northern Mexico.

State officials have asked Mexico’s Interior Ministry to transfer inmates connected with federal offenses out of the prison, which has become significantly overcrowded as authorities crack down on organized crime, Medina said Monday.

— CNN’s Rey Rodriguez in Mexico City, journalist Victor Badillo in Monterrey and CNNMexico.com contributed to this report.