MONTERREY, Mexico More than 140 inmates escaped via the main entrance of a prison near the U.S. border on Friday in the biggest Mexican jailbreak since the government began its war on drugs four years ago. Hours later, suspected hitmen blew up a car outside a police station near the business hub of Monterrey in the latest act of brinkmanship between drug gangs and officials. In a brazen move underscoring Mexico's weak prison system, inmates slowly filed out of the main vehicle entrance of a prison in Nuevo Laredo across from Texas early on Friday, two police sources in northern Tamaulipas state said. 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 this year, when a cartel split into rival factions. 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. Several national media received letters signed by drug gangs that promised more attacks using cars stuffed with explosives, national newspaper Reforma reported online. Nuevo Leon and the neighboring state of Tamaulipas are often caught 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 detonating 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. Mounting insecurity in Mexico is a threat to Latin America's No. 2 economy as investors question the safety of doing business. The violence is also a worry for Washington. U.S. Secretary of State Hillary Clinton warned in September that Mexico was starting to resemble Colombia at the height of its cocaine-fueled insurgency in the 1980s and 1990s. 'Very severe collusion' In Nuevo Laredo, soldiers and federal police surrounded the prison. Tamaulipas' security chief Antonio Garza told local radio that the jail's director was reported as missing along with 141 inmates. He confirmed the vehicle entrance was used as the escape route and blamed prison guards for complicity. "I am sure that inside (the prison) there was very severe collusion (between guards and drug gangs)," he said. The head of the state's jail system was also suspended pending investigation, Garza added. The federal Interior Department blamed the breakout on local authorities, saying they did not properly guard the facility. "The absence of effective methods of guarding and control by local authorities is deplorable, and it has caused frequent escapes from prisons that put the public at risk," the department said in a statement. It called on state authorities to clean up their prison and judicial systems by increased screening and vetting of corrections officers. In past cases, prison guards often underpaid or under threat from gangs have been implicated in prison escapes. It was not immediately clear who was behind the prison break, but police sources said the Gulf cartel may have offered to free Zeta gang members, their former allies, on condition that they switch sides. The escape follows a string of breaches across northern Mexico, underscoring the challenges that President Felipe Calderon faces as he battles powerful drug cartels. Authorities have arrested or killed at least seven top drug cartel leaders in the last year, but have not succeeded in shutting down the gangs. Calderon, who sent thousands of troops across the country to fight drug gangs, has vowed to clean up prisons that in the past have allowed drug lords to live in luxury or escape when they please. But the conservative leader has struggled to contain corruption and lawlessness in the prison system, which is run partly by state and local governments. 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. 141 inmates walk out of Mexico prison - World news - Americas - msnbc.com -------------------------------------------------------- The United States cannot continue to allow a terrorist state to be on the border with the country with the largest arsenals in the world. It is time to remove the evil from the United States and force Mexico to disarm.