A total of 85 prisoners escaped from a jail in northern Mexican state of Tamaulipas, the largest prison break in the state's history, officials said on Friday.
The inmates escaped the Center for the Serving of Sanctions Jail in Reynosa early Friday, using a ladder and with the help of two guards, state Secretary General Hugo Andres Araujo told a press conference.
State authorities are investigating the incident, but no one has yet been arrested, he said.
The prison is located near a highway linking Nuevo Leon state capital Monterrey to Reynosa, which borders McAllen in southern U.S. state of Texas.
As one of Mexico's most violent states, Tamaulipas has seen deadly rivalry between Los Zetas and the Gulf Cartel, two drug-trafficking gangs.
Tamaulipas town San Fernando was the scene of the Aug. 24 massacre of 72 migrants from Guatemala, El Salvador, Ecuador and Brazil, who were shot dead by suspected Los Zetas members.