The incident took place in the early hours of Wednesday when unknown gunmen tried to seize the plant but faced resistance organized by the employees.
"I firmly condemn crude clashes that took place at the Cruz Azul plant in the town of Tula where, according to the recent information, eight people died, 11 were injured and nine were detained," Omar Fayad Meneses wrote on his Twitter page on late Wednesday.
He also tasked the regional Interior Ministry and the prosecutor's office with investigating the incident as well as facilitating the dialogue between the conflicting parties.