The bullet-riddled bodies of 16 men were found Monday inside an abandoned van in a western Mexico region mired in drug violence, an official said.
The bodies were discovered on a highway outside the town of Coyuca de Catalan in the Pacific coast state of Guerrero, said Fernando Monreal, a deputy state prosecutor.
"All the bodies had wounds from bullets of various calibers. They are all males and at the moment their identities are unknown," Monreal said.
Soldiers and federal police were sent to the area, a region known as Tierra Caliente that has been the scene of a turf war between two drug cartels, La Familia Michoacana (The Michoacan Family) and the Knights Templar.
A message attributed to La Familia Michoacana was painted on the vehicle, the newspaper Reforma reported on its website, citing police sources.
Guerrero state governor Angel Aguirre told reporters that, according to the preliminary investigation, the victims were from the state of Michoacan.
Last month, authorities discovered 11 bodies scattered along a stretch of road in Tierra Caliente, which borders the states of Mexico and Michoacan.
The bodies found on August 26 bore signs of torture and had bullet wounds in their heads. Letters allegedly signed by the Knights Templar threatening rival gangs were found near the bodies.
The federal government deployed more than 7000 troops and police officers to Guerrero in October 2011 to bring down violence, especially around the state's tourist hub of Acapulco.
Some 60 000 people have been killed in drug-related violence in Mexico since 2006, when President Felipe Calderon deployed the military to combat cartels, according to estimates from non-governmental organizations.
The country's drug cartels often leave threatening messages on bodies that have been left inside abandoned vehicles, hanging from bridges or dumped on sides of roads.
The bodies of 14 men were found in an abandoned vehicle in the central state of San Luis Potosi on August 9.