( CNN ) -- The 129 inmates who escaped from a northern Mexico prison did not flee through a tunnel , as authorities first reported . They walked out the front door . Federal and local authorities launched a manhunt after the inmates escaped Monday in Piedras Negras , across the border from Eagle Pass , Texas . Authorities arrested 16 employees , including the prison director , after the escape . Politician Manlio Fabio Beltrones said the prison break highlights a larger issue in Mexico . `` The crisis in the Mexican prison system is serious and must be addressed urgently , '' Beltrones said . Mexican President Felipe Calderon condemned the escape , calling it `` deplorable '' in a series of Twitter posts Tuesday . `` In the past six years , more than 1,000 inmates have escaped from state prisons . From the federal prisons , not one , '' he wrote . 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 . In February , 30 inmates fled after a riot in a prison in Monterrey , Mexico . Authorities originally said the inmates in the latest escape slipped through a 23-foot tunnel , sliced through a chain-link fence and ran through an empty lot . But they released new information saying the inmates went through the front door . `` It is hard to believe that they went through that tunnel , '' said Jose Luis Moran , the public safety secretary for the Mexican state of Coahuila . 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 . Police 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 . More on Mexico : Gulf Cartel boss arrested . CNN en EspaÃ±ol 's Mario Gonzalez and Rey Rodriguez and CNNMexico.com contributed to this report .
Prison director is among 16 employees arrested after the escape . The prison was built in the 1970s and has a capacity of about 1,200 inmates. Police set up blockades on roads leading to the United States . President : More than 1,000 inmates flee from state prisons in six years .