Nine bodies have been found piled on a roadside in Mexico's Gulf coast state of Veracruz, authorities say.
The state public safety department called the killings "a reaction to the results of work being done to fight crime".
Veracruz Governor Cuitlahuac Garcia suggested the crime involved gangs.
"We are not going to allow any acts of revenge between criminal groups," Garcia said.
He also said past Veracruz administrations had accords in place with drug gangs that operate in the state.
"We are going to take resounding action against all the criminal groups that before had agreements with past state administrations," Garcia said, adding that gangs "are a little angry" that such agreements no longer exist.
Local media reported a handwritten message found at the scene threatened authorities and was signed by "the four letters", commonly a reference to the Jalisco Cartel.
There are four letters in the initials of the cartel's formal name, Jalisco New Generation Cartel.
The bodies were found in the township of Isla, near the crime-plagued port of Coatzacoalcos.
10 bodies found in abandoned car
The grisly discovery came a day after assailants left the bodies of eight men and two women in front of the governor's office in the central state of Zacatecas.
The bodies were found crammed into an SUV left before dawn on Thursday near a Christmas tree in the main plaza of the state capital, also named Zacatecas.
Francisco Murillo, the Zacatecas chief prosecutor, said seven of the 10 bodies had so far undergone an autopsy and all died of "asphyxiation by strangulation".
Six had injuries suggesting they had their feet and hands bound. One showed possible signs of torture.
President Andres Manuel Lopez Obrador has been unable to significantly reduce homicides in Mexico since coming to power in late 2018.
There were 31,615 killings in the first 11 months of 2021, a decline of just 3.6 per cent from the 32,814 in 2020.
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