They were found by the authorities on Monday on a dirt road close to the town of Camargo, which is across the US border from Rio Grande, Texas.
The Tamaulipas state prosecutor's office said they were found after local residents complained about burning vehicles.
Responding officers found two burning vehicles that contained the bodies. The authorities believe the people were not killed at the site of the vehicles, as there was no evidence of them being shot nearby.
An official confirmed that the killings were first discovered by residents on Friday, but the authorities were not told until earlier this week as they were too scared to report them.
Some Guatemalan Maya families said they feared their relatives were part of the group found, according to Reuters.
One father, Santos López, told Vice News that his daughter was among a group attempting to reach the US border, but confirmed that he lost contact with her on Friday.
While Ramiro Coronado told NBC News that he feared for his 31-year-old nephew, who had been attempting to cross the border last week.
“I only feel pain and sadness,” he said on Monday. “It was the first time he'd tried to travel to the United States to improve his life and that of his family. He's leaving behind a wife and two children,” Mr Coronado added.
The Guatemalan foreign ministry said in a statement on Monday that it was working with Mexico to determine if any of its residents were among the victims.
The ministry said that it had activated consular aid protocols, while the Tamaulipas state prosecutor’s office said that the case was being investigated.
In a statement on Twitter on Monday, Guatemala’s Congress said that lawmakers “mourned the tragic death of our migrant brothers from San Marcos,” but did not reveal any further details.
While Mario Ernesto Galvez, a Guatemalan lawmaker, claimed that 13 of the victims were from his San Marcos province, and listed their names in a statement.
The immediate family members of missing Guatemalan residents had their DNA swabbed at the country’s foreign ministry on Monday to have it compared with the bodies found, which have still not yet been identified.
Carmago has faced high numbers of drug and migrant smuggling incidents in recent years, as large parts of the area are controlled by organised crime groups, who make money off people and items crossing the border to the US, according to CBS News.
The town has historically been run by the Gulf cartel, but in recent years it has faced competition from the Northeast cartel, leading to a greater number of incidents at the border.
There has also been an increase in Guatemalan migrants attempting to cross the US border in recent months, as the economic impact from the coronavirus pandemic and two severe hurricanes have devastated some areas of the country.
In January 2020, 21 bodies were found in vehicles close to the nearby town of Ciudad Mier, while in January 2019, 15 charred corpses were found among 24 dead close to the border in Miguel Aleman.