HOUSTON -- Texas border patrol agents were on alert Tuesday for more than 130 inmates who escaped from prison in a Mexican border town.
The inmates escaped through a 21-foot tunnel from the prison in Piedras Negras, and more than half had been serving time for federal crimes, including drug trafficking, officials told ABC News. Piedras Negras is just across the border from Eagle Pass, Texas, about 140 miles southwest of San Antonio.
The attorney general of Coahuila state, Homero Ramos Gloria, said that three employees of the prison, including the director, were being questioned about the potential involvement of staff in the mass breakout, according to Mexican media reports. Investigators also detained a dozen prison guards.
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Ramos told a Mexican television station that the escapees' tunnel, which was 4 feet wide, "was not made today. It had been there for months."
"We have 132 inmates escaping through a tunnel," said Ramos, "and it doesn't make sense."
The inmates staged their escape just after 2 p.m. Monday, according to Mexican media. The inmates overpowered guards, escaped through the tunnel within 15 minutes, cut a chain-link fence and went through a vacant lot.
U.S. Customs and Border Protection officials told the Los Angeles Times that they were aware of the escape and have been in touch with Mexican officials.
"CBP is aware of the reported jail break in northern Mexico, and out of an abundance of caution, has placed its officers and agents in the Eagle Pass, Texas, area on alert," said spokesman Dennis Smith. "At this point, CBP has no reports of escapees attempting to cross the border."
U.S. Customs and Border Protection has two stations in Eagle Pass, but Smith declined to say how many agents are stationed there, citing security concerns.
He said officials have not received any reports of Mexican fugitives from the prison break trying to cross the border.
"We will continue coordinating with our Mexican counterparts as we monitor this situation," Smith said.
Two years ago, more than 150 inmates escaped from a prison in Nuevo Laredo, across the Rio Grande from Laredo, Texas. Forty-one guards were charged with aiding in that escape, the largest in Mexico in recent memory.
During a 2009 escape at a prison farther south in Zacatecas, more than two dozen men dressed as federal police officers raided the prison and freed more than 50 members of the Zetas cartel.
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