Police in Mexico have found the bodies of 14 people in an abandoned van outside the city of San Luis Potosi.
The authorities say the victims, who were all male, had been kidnapped in neighbouring Coahuila state.
The vehicle was found early on Wednesday near a petrol station.
Police say the 14 people were probably killed by one of Mexico's violent drug-trafficking gangs operating in the area.
"According to the initial information, everything indicates that it was the work of organised crime," Gabriela Gonzalez, a spokeswoman for Mexico's Prosecutor's Office told the AFP news agency.
A statement from the prosecutor's office says that the victims were "kidnapped in Coahuila state, they made a stop in Zacatecas and were killed on their way to the city of San Luis Potosi," which is the state capital.
This is the latest in a series of recent massacres in northern Mexico, but the first in San Luis Potosi state. The motive is unclear.
Mexican police have blamed several previous atrocities on conflict between rival drugs gangs.
The Zetas criminal gang has been fighting the Gulf and Sinaloa cartels for control of smuggling routes into the US.
But there have been cases when the victims were poor people trying to cross illegally into the United States who had been targeted by criminal organisations.
President Felipe Calderon - who leaves office later this year - deployed the army in 2006 to combat the cartels with mixed results.
Critics say the confrontation cost the lives of thousands of innocent people.