It seemed a run-of-the-mill prison riot, though one that left 44 inmates beaten or knifed to death. In fact, the violence on Sunday in northern Mexico served as cover for a massive jailbreak by members of the country's deadliest criminal gang, the Zetas.
Authorities on Monday revealed that 30 Zetas henchmen escaped from the maximum-security prison in Apodaca during the brawl — with the apparent complicity of guards and possibly other top officials.
The deadly violence underscored the abysmal condition of Mexican prisons, which are woefully overcrowded, rife with corruption and prone to high-profile escapes.
The warden, three other penitentiary officials and 18 guards have been removed or suspended and detained for questioning, said Rodrigo Medina, governor of Nuevo Leon state, where Apodaca is located.
All of those killed, he added, were from the Zetas' bitter rival, the Gulf cartel. The two gangs, former allies, are now at war for control of part of Mexico's drug trade and other criminal enterprises.
"We can say without a doubt that this was premeditated and planned," Medina said at a news conference, where he announced a nearly $800,000 reward for information leading to the capture of the escapees.
"This isn't a thing where, in the middle of a riot, it occurred to these people to escape." Medina said. "There was a plan, which undoubtedly relied on the complicity of some officials."
While overcrowding, violence and corruption plague penal systems throughout Latin America, the problems are especially acute in Mexico, where a military crackdown on drug cartels has helped fill cells, often to more than double their intended capacity.
Frequently, entire criminal enterprises are run from inside jailhouse walls; in a recent wave of telephone extortions, investigators found that the vast majority of calls demanding money originated from prisons.
Mexico's National Human Rights Commission says 467 inmates have been killed since the beginning of 2009 — shot, bludgeoned, stabbed or burned to death.
The prison at Apodaca, just north of the major industrial city of Monterrey and about 100 miles from the U.S. border, reportedly held twice the number of men it was built to accommodate and had been flooded recently by members of both the Zetas and Gulf gangs. Authorities make some effort to separate gangs within a prison, but divisions are easily breached.
Medina noted that an "unprecedented" number of arrests in the last couple of years, primarily of drug traffickers and the gunmen, kidnappers and extortionists who work with them, had resulted in an "exponential" burst in prison populations, "with all the complications and difficulties that entails."
Authorities said the fighting Sunday apparently started about 2 a.m., when Zetas using sharp instruments, stones and clubs attacked inmates belonging to the Gulf cartel. As violence spread from one cellblock to another, 30 Zetas escaped, apparently with minimal effort, leading authorities to conclude they had inside help from guards or other officials.
"It is hard for us to [acknowledge] the treason, the corruption and the complicity of a handful of officials, which trips up the work of good police, soldiers and marines who daily risk their lives," Medina said.
One of the escaped inmates was identified as Oscar Manuel Bernal, alias "El Spider," a local Zetas lieutenant arrested in 2010 in the assassination of an army general who days earlier had taken over as police commander in the Nuevo Leon city of Garcia.
The prison systems have proved themselves notoriously porous. Scores of inmates have escaped over the years, including the fugitive multibillionaire and today most powerful cartel leader, Joaquin "El Chapo" Guzman. He is said to have bought his way out of a maximum-security prison in 2001, gliding out in a laundry cart.
In 2009, guards were caught on camera calmly watching as 53 inmates walked out of a prison in the central state of Zacatecas. In December 2010, 140 inmates escaped from a prison in violent Tamaulipas state, which neighbors Nuevo Leon; the warden vanished. And in August of the same year, the warden of a prison in Gomez Palacio, in central Mexico, was jailed for allowing inmates to borrow guns from the guards, leave at night and go on killing sprees aimed at their rivals.