A fire swept through a cell block in a northern Mexican prison early Friday, killing 14 inmates.

The fire broke out around 3 a.m. at the prison in the town of Apodaca on the outskirts of Monterrey, said Jorge Domene, a spokesman for the Nuevo Leon state government. He said the wing had once been the prison's psychiatric ward but was currently being used as a normal cell block.

He said the fire was under investigation and there were no further details.

The blaze may have been caused by a short circuit, possibly in a television set, according to an official with the Nuevo Leon state Public Safety Department, who spoke on condition of anonymity because he was not authorized to speak about the fire.