The bullet-ridden bodies of 18 people were discovered after what appeared to have been a shootout between members of rival drug cartels in northern Mexico.
The bodies were found in a remote, rural area of the north-central state of Zacatecas, state security department spokeswoman Rocío Aguilar said on Friday.
There was evidence the deaths in the township of Valparaiso resulted from a confrontation between gunmen from the Sinaloa and Jalisco cartels, she said.
Zacatecas, once dominated by the old Zetas cartel, is being fought over by a dizzying number of cartels. Those jockeying for turf in Zacatecas include the Sinaloa, Jalisco, Gulf and Northeast cartels as well as remnants of the Zetas who call themselves “Talibans”.
The gunbattle came two days after the bodies of two abducted police officers were found hanging from an overpass in the Zacatecas state capital and seven people were discovered shot to death in a neighbouring city.
The policemen were officers from the neighboring state of San Luis Potosi who had been reported missing earlier.
Drug cartels have hung the bodies of victims from overpasses before as a message to rivals or to authorities, but seldom do so with members of law enforcement.
In the nearby city of Fresnillo, police later found the bullet-ridden bodies of four women and three men. One man and a woman were found wounded at the scene of the attack, along with five children who had not been harmed.
The deaths in Zacatecas also follow a flare-up in violence on the US-Mexico border where 19 people were killed last weekend.