"We have the bodies of 14 males aboard a Mercedes-Benz van that had been reported stolen," San Luis Potosi state Attorney General's Office spokeswoman Gabriela Gonzalez told EFE Thursday.
The victims "were apparently kidnapped in Coahuila state", which is also in northern Mexico, and taken to San Luis Potosi.
The van containing the bodies was found on the San Luis Potosi-Zacatecas highway.
The vehicle was found around 4.30 a.m. near the La Posta service plaza by authorities acting on an anonymous tip.
Investigators have gathered information indicating that the killers "made a stop in the state of Zacatecas" and the victims "were executed" on the drive to San Luis Potosi, Gonzalez said.
AG's office crime scene specialists and investigators are gathering evidence "to do all the necessary work", Gonzalez said.
No messages were left with the bodies, as is often the case in hits staged by drug cartels, Gonzalez said, adding that the bodies were taken to the coroner's office.
"Based on the characteristics, we consider that we are dealing with an organized crime incident. However, the Attorney General's Office has opened an investigation of this incident ... and we'll see if later it is transferred to federal authorities," Gonzalez said.
More than 50,000 people, according to official figures, have died in drug-related violence since late 2006.