Mexican authorities have sacked the director of Apodaca prison in the northeast after jailed members of the Zetas drug cartel stabbed and bludgeoned 44 members of the rival Gulf cartel to death before escaping en masse.
The escape on Sunday was apparently aided by prison authorities, Mexican officials said.
Rodrigo Medina, governor of the northern state of Nuevo Leon, said on Monday that the prison director and three other officials were being investigated after their dismissal.
The same was done with 18 prison guards, he said.
"Unfortunately, a group of traitors has set back the work of a lot of good police," Medina said.
"The most important thing is to make sure that the people working on the inside are on the side of the law, and that they not be corrupted and collaborate with the criminals, as the investigations indicate they presumably did."
Deadly fights happen periodically in Mexico's prisons as gangs and drug cartels stage jail breaks and battle for control of prisons, often with the involvement of officials. Sunday's riot was one of the deadliest so far.
Up to 31 prisoners died in January during a prison riot in the Gulf coast city of Altamira in Tamaulipas state, which borders Texas.
Another fight in a Tamaulipas prison in the border city of Matamoros in October killed 20 inmates and injured 12.
Blunt instruments and knives
Medina did not say how the escape was carried out, but he noted that no members of any gang had broken into the prison to help their colleagues escape, as has happened at other Mexican prisons.
Nor were any firearms smuggled into the facility; all of the deaths apparently occurred with blunt instruments or improvised knives.
Medina confirmed that all 30 escaped inmates were linked to the Zetas cartel, a brutal gang founded by deserters from an elite Mexican military unit.
He did not say what crimes the escaped inmates had been convicted of, but said 25 of the 30 were in the prison on federal charges, which often involve drug trafficking or illegal weapons possession.
Medina offered a reward of 10 million pesos (almost $800,000) for information leading the arrest of those involved in the mass escape.
The Zetas and Gulf cartels were allies before splitting in 2010 and they have been fighting turf battles in Monterrey and elsewhere in northeastern Mexico.
A riot at a prison in the border city of Juarez in July last year killed 17 inmates. Mexican authorities detained the director and four guards over that clash.
Surveillance video showed two inmates opening doors to let armed prisoners into a room where the slain victims were reportedly holding a party.
In 2010, 23 people were killed in a prison riot in Durango city while a riot in Gomez Palacio, another city in the northern Mexican state of Durango, killed 19 people in 2009.
More than 47,500 people have been killed in drug-related violence since 2006, when President Felipe Calderon intensified Mexico's crackdown on organised crime.