Mexican security officials say at least 40 people have been killed across the country in a 24-hour period.

Police found the bodies of seven men and three women in the northern city of Torreon on Saturday. Police have not said if they have suspects yet. But Coahuila state, where Torreon is located, is a battleground for two powerful drug cartels — the Zetas and a cartel headed by Joaquin “El Chapo” Guzman.

Late Friday, gunmen shot and killed 20 people inside a bar in the northern city of Monterrey. Local media say more than two dozen attackers opened fire on the patrons at the bar in a busy commercial district.

Monterrey has been the scene of deadly battles involving drug cartels fighting over routes into the United States.

Earlier Friday, Mexican police said the bodies of 10 people were found shot on the outskirts of Mexico City.

Police say the victims were found in the Valle de Chalco area blindfolded and with their hands tied.

Police suspect the killings could be drug-related, but say they are continuing their investigation.