The 149 prisoners slowly filed out the main entrance of a prison in Nuevo Laredo across from Texas in the early hours of Friday, said two police sources in northern Tamaulipas state, in a brazen move underscoring Mexico's weak prison system.
Later on Friday in the small town of Zuazua on the northern outskirts of Monterrey, an SUV exploded, injuring two people and knocking out power. It was the first such explosion near Mexico's richest city, a business center with close U.S. ties.
While authorities declined to say if the two incidents were linked, Zuazua lies on the highway between Monterrey and Nuevo Laredo and the area has become a major flashpoint in the drug war since early 2010, when a cartel split into rival factions.
"Yes, there was an explosion. A car exploded outside Zuazua's police station," said a spokeswoman for Zuazua's civil protection service who declined to be named.
Jorge Domene, a spokesman for Nuevo Leon state that includes Zuazua and Monterrey, blamed organized crime and said the explosion was aimed at intimidating police. "It is obvious this is a message to the authorities," he told Milenio TV.
Rivals from the Gulf cartel and the Zetas gang are fighting for Nuevo Leon and the neighboring state of Tamaulipas in a wider cartel war across Mexico over smuggling routes into the United States and local criminal rackets. The war has killed more than 30,000 people since late 2006, according to official figures. Media reports put the sum at more than 33,000.
In a new tactic, suspected drug hitmen began using explosives in cars this year, first in Ciudad Juarez, Mexico's deadliest city across from El Paso, Texas, in July and then in Ciudad Victoria in Tamaulipas in August.
In Nuevo Laredo, soldiers and federal police surrounded the prison. Many of the escaped prisoners were believed to be serving sentences for drug trafficking.
"They left by the front door, which points to complicity of the prison guards," said a police source who declined to be named for security reasons.
The attorney general's office confirmed the prison break in the town across from Laredo, Texas, but gave no more details.
The federal government said on Friday the prison break was deplorable and urged the state government to take action to find the fugitives and clean up its prison system.
In September, 85 prisoners escaped from a prison in the nearby border city of Reynosa. Authorities discovered in July that prison officials had allowed convicts out of a prison in northwestern Durango state to carry out revenge attacks before returning to cells for the night.