Over 130 inmates escape Mexican prison near Texas border

(CBS/AP) PIEDRAS NEGRAS, Mexico - More than 130 inmates escaped through a tunnel from a prison in northern Mexico on Monday, setting off a massive search by police and soldiers in an area close to the U.S. border. The prison is located in Piedras Negras, a city just across the border from Eagle Pass, Texas.

Officials say they have so far found three of the escapees - female inmates found hiding in a prison visiting area.

Federal police units and Mexican troops, including 70 members of an elite military special forces unit, are searching for the inmates who escaped through a tunnel 21 feet long and four feet in diameter on Monday. They then reportedly cut their way through a chain link barrier and escaped onto a neighboring property.

The tunnel "was not made today. It had been there for months," Coahuila Attorney General Homero Ramos told the Milenio TV station. Authorities say they also found ropes and electric cables they believe were used in the mass escape.

Collusion between guards and drug gangs has played a role in past escapes, and federal authorities have been pushing to have all state and municipal police and law enforcement officials submit to background and anti-drug checks, as well as vetting for possible links to organized crime.

The U.S. Customs and Border Protection said it was aware of the prison break and placed officers in the Eagle Pass area on alert, but has not received any reports of escapees attempting to cross the border, according to an e-mailed statement.

Coahuila, where Monday's prison break took place, has seen a wave of violence tied to the Zetas' battles with the Sinaloa cartel, allies of the now weakened Gulf Cartel.

Authorities in Coahuila did not say which gang was believed to be behind the escape.

In Piedras Negras, family members had gathered outside the prison to hear word of their loved ones.