Twelve people believed to be members of a self-defense group were killed in the western Gulf Coast state of Veracruz and their bodies dumped on a dirt road, local authorities said on Monday.

The bodies were found with their feet and hands bound, according to local media citing a police report on the incident in the volatile Las Choapas municipality.

The area is about 363 kilometers (225.5 miles) south of the port city of Veracruz, the state capital.

The Veracruz security ministry said in a statement the victims were “executed” and early reporting indicated they were members of “self-defense groups,” which have sprung up in Mexican regions riddled with drug cartel violence.

Cuitlahuac Garcia, the Governor of Veracruz, said initial reports indicate a split in one such self-defense group led to the violence.

“The abuses and threats between them caused a confrontation between them and had this unfortunate outcome,” Garcia said.

Self-defense groups are common in some parts of Mexico, where authorities have struggled to bring about law and order amid internecine cartel violence.

These vigilante forces have helped contain violence in some crime-stricken areas or shielded the local population. But some of them have also struck alliances with criminal gangs in exchange for weapons and protection, analysts say.

Authorities often accuse self-defense groups of being criminal organizations, or having deep ties with certain cartels.

In the first 11 months of last year, Veracruz was the eighth most violent state in Mexico, with 1,320 homicides recorded, according to federal authorities.

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