Armed assailants burst into a prison in the northern border town of Miguel Aleman on Tuesday and helped a dozen inmates escape, Mexican authorities said.

The incident occurred around 2:00 a.m. and two of the escapees were convicted murderers, the Tamaulipas state Attorney General's Office said in a statement.

Fifteen armed men drove up in several vehicles and overpowered the guard at the access door, overcame the commander on duty, stole the keys to the cells and set the prisoners free, the AG's office said.

Federal, state and municipal authorities have joined forces to hunt down the fugitives, the statement said.

Jailbreaks and prison riots are all too frequent in Mexico.

Last September, 131 convicts escaped from the Piedras Negras Prison in Coahuila, in what became one of the largest jailbreaks ever to be pulled off at a Mexican prison.

Last December, 24 people died in a riot and attempted escape from a jail at Gomez Palacio in the northern state of Durango. EFE