NORTHERN MEXICO (CNN) -- Authorities in northern Mexico detained a prison director and two other officials after 129 inmates escaped from the facility through a tunnel, officials said.
The three prison leaders will be detained for 30 days during an investigation, Coahuila State Attorney General Homero Ramos told CNN en Español.
Local and federal authorities were searching for the inmates and U.S. officers were on alert after the prison break, which occurred Monday in Piedras Negras, across the border from Eagle Pass, Texas, and about 150 miles from San Antonio.
The inmates escaped one by one from the minimum-security facility, slipping out through a 7-foot-long tunnel, cutting through a chain-link fence and running through an empty lot, according to a statement from the Coahuila state attorney general. The tunnel, which was about 4 feet wide and nearly 10 feet deep, began in a wood shop inside in the prison, authorities said.
Officials originally said that 132 inmates had escaped but adjusted the figure to 129 after finding three inmates hiding in another part of the prison, state security spokesman Sergio Sisbeles said. Of the escapees, 86 were federal prisoners and 43 were incarcerated on local charges.
Mexican authorities were offering a reward of nearly $16,000 for information leading to the capture of each escaped inmate.
Local and federal authorities are searching for the inmates, and police have set up blockades on roads leading to the Mexico-U.S. border.
U.S. Customs and Border Protection placed its officers and agents in the area on alert, a homeland security official said.
"At this point, CBP has no reports of escapees attempting to cross the border. We will continue coordinating with our Mexican counterparts as we monitor this situation," the source said.
Mexican President Felipe Calderon condemned the prison break in a series of Twitter posts Tuesday, calling it "deplorable."
"In the past six years more than 1,000 inmates have escaped from state prisons. From the federal prisons, not one," he wrote.
In February, 30 inmates fled after a riot in a prison in Monterrey, Mexico.
The largest escape during Calderon's six-year term occurred in December 2010, when 151 inmates escaped from a local prison in the Mexican border city of Nuevo Laredo.