The bodies of five university students were found stuffed in a vehicle on a dirt road in north-central Mexico, authorities said Monday.
The car and the bodies of the victims, all young men, 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.
Diego Sinhue Rodríguez, the governor of the state of Guanajuato, pledged an "exhaustive" investigation into the killings.
"I deeply regret the cowardly act where the lives of young people were taken," wrote Javier Mendoza Márquez, the mayor of Celaya, on social media.
The Latina University of Mexico wrote in a statement Monday that all five were students there. It said the university suspended classes Monday in mourning.
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.
The Jalisco cartel is known for producing millions of doses of deadly fentanyl and smuggling them into the United States disguised to look like Xanax, Percocet or oxycodone. Such pills cause about 70,000 overdose deaths per year in the United States.