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Police in the northern Mexico state of Sonora say six severed human heads have been found in a plastic cooler on a roadside.
A Sonora official who was not authorized to be quoted by name says the grisly artifact was reported to an emergency number.
Coverage of violence in Mexico on Globalnews.ca:
There was no immediate information on the identity of the men, nor were their bodies immediately found.
The heads were discovered Friday near the city of Ciudad Obregon.
READ MORE: 250 skulls found in clandestine graves near Veracruz, Mexico over past few months
Drug gangs often leave severed heads as a warning to rivals or authorities.
Until now, Sonora has not seen as much drug violence as other northern states.