The bodies of five young men were found stuffed in a vehicle on a dirt road in north-central Mexico, authorities said.
Diego Sinhue Rodríguez, the governor of the state of Guanajuato, pledged an “exhaustive” investigation into the killings.
The car and the bodies were found Sunday in a rural area on the outskirts of the city of Celaya, which has seen a spate of drug cartel violence in recent years. The area is located outside a local university.
Local media reported the men had been shot to death, but prosecutors did not immediately confirm that.
In June, a drug cartel set off a car bomb in Celaya aimed at law enforcement, killing a National Guard officer.
National Guard officers were reportedly responding to information about a car parked with what appeared to be bodies inside. As they approached, the vehicle exploded, sending officers flying.
Authorities blamed the Santa Rosa de Lima cartel, which for years has fought a bloody turf war with the Jalisco cartel for control of Guanajuato.