Some 132 inmates have escaped from a jail in northern Mexico, sparking a search by federal police and soldiers in an area close to the US border.
Coahuila state's attorney general Homero Ramos Gloria said the director of the prison in Piedras Negras and two other employees have been detained for investigation.
Mr Ramos said that 86 of the inmates were serving sentences or pending trials for federal crimes, such as drug trafficking, and the rest faced state charges.
In December 2010, 153 inmates escaped from a prison in the northern city of Nuevo Laredo, opposite Laredo, Texas.
Authorities charged 41 guards with aiding the inmates in that escape. Mexico's drug gangs frequently try to break their members out of prison.