The jailbreak occurred in the afternoon, and authorities have asked the US for help to locate and arrest the inmates, Xinhua quoted Jose Luis Moran, public security minister of Coahuila state to which Piedras Negras belongs as saying.
Some media reports said the inmates tied one of the guards and escaped through a tunnel.
Other reports, however, said the guards were threatened with guns and knives and the inmates fled through the main gate.
Mexico City: At least 30 prisoners escaped Monday from a Mexican jail in the Mexican-US border city of Piedras Negras, said authorities.
First Published: Tuesday, September 18, 2012, 13:58