The burnt bodies of 19 people have been found close to the Mexican border with the US, according to officials from Tamaulipas state.
Police found two burnt-out vehicles on Saturday and initial findings indicate the people were shot and then set alight.
Violent drug gangs operate in the area, where migrants also try to cross into north America.
An official said the victims may be undocumented migrants, reports AFP.
The north-eastern state of Tamaulipas is known for violent killings and disappearances, often linked to powerful drug cartels who battle for territory.
The Mexican government is fighting what it calls a war on drugs, and its security forces have previously been accused of detaining suspects who later go missing.
In the latest incident the bodies were found near the town of Camargo which borders the US state of Texas.
Autopsies are underway, but the Tamaulipas state prosecutor’s office said that the poor condition of the remains was complicating the procedures.
An investigation has begun to determine if the people killed were migrants travelling from Guatemala to try to reach the US.
Officials have contacted the Guatemalan consular authorities in Mexico “to provide the necessary information and try to identify some of the people believed to be Guatemalan migrants,” an official told AFP news agency.
In recent weeks a group of about 7,000 people had been travelling north from Guatemala to find a better life in the US, but the group was disbanded by security forces near the border with Honduras.
Every year thousands of people from Central American attempt to make the long journey, often on foot, to the US through Mexico, many fleeing poverty and violence.
Drug gangs often extort money from migrants travelling through their territories, and run people smuggling operations that take advantage of people’s desperate wish to reach north America.
In 2019 24 corpses were found in neighbouring town Miguel Aleman, 15 of which were burnt.
Nearly 500 migrants from Central and South America died in 2019 near the US-Mexico border, according to the UN.
