Mexican police found six severed heads, including four gruesomely left in coolers on a roadside, amid a wave of drug-related violence that has claimed hundreds of lives in recent months.
"We found four human heads in as many coolers ... And the remains have not yet been identified," said a statement from the office of the governor of Durango state on Friday.
The remains were discovered six kilometers (four miles) from the state capital of Durango, along the same road where a shootout on Tuesday left eight gunmen dead.
Next to the severed heads were "intimidating and threatening messages" aimed at the leaders of drug cartels, the statement said.
The violence that has gripped Mexico in recent weeks -- including the murders of several top law enforcement officials -- is believed to be mostly related to the government's stepped up fight against drug trafficking.
To the north in Ciudad Juarez, a town across the border from the United States, 10 more bodies were found in various locations, including two whose heads had been cut off and left in plastic bags, a Chihuahua state official said.
Menacing messages aimed at druglords including Joaquin Guzman, leader of the powerful Sinaloa cartel, were left alongside corpses in two of the Ciudad Juarez locations.
Rival drug gangs battling for control of their turf have triggered a surge in bloodshed in the past few weeks in this city and nearby towns, with 398 murders this year alone in Ciudad Juarez, according to officials.
At stake is access to the world's biggest market for narcotics, most of which slip through the border to the United States.