Police in the western Mexico state of Jalisco found a pickup truck loaded with five bodies Sunday, all covered in plastic bags.
Eduardo Almaguer, the Chief State Prosecutor, said the discovery came early Sunday after police received a tip about a convoy of armed men travelling in pickup trucks. Officers and soldiers went to check out the report and detained 10 suspects and the trucks on the outskirts of the state capital of Guadalajara.
Almaguer said officers found the five bodies in the back of one of the trucks. Investigators were working to identify the dead.
Jalisco is home to Mexico's fastest-growing drug gang, the Jalisco New Generation cartel.
Elsewhere, the leftist Democratic Revolution Party said one of its mayors was shot to death by assailants in the southern state of Oaxaca. The party said the victim was Jose Villanueva Rodriguez, mayor of Ocotlan, a town south of the colonial city of Oaxaca.
The party condemned the killing and called on authorities to find and punish the killers.
Previously the party said 75 mayors have been killed in Mexico over the last decade, not counting Villanueva Rodriguez.
It said 16 killings of mayors have occurred since President Enrique Peña Nieto took office in December 2012.
Mayors in Mexico have little protection and are frequently vulnerable to extortion demands by drug cartels.