Mexican police said they have found the bodies of 24 men who were bound and shot to death execution-style outside the capital.
The bodies found on Friday represent one of the largest single mass executions in Mexico in recent memory.
Police and soldiers were at the scene of the crime in a rural area just west of Mexico City, which has been marked by gangland slayings and land disputes between farming communities.
The killings are "without doubt" linked to organized crime, said Alberto Bazbaz, the attorney general of Mexico State, which borders Mexico City.
"The only thing we have to identify them is that they all appear to be between 20 and 35, all of them have military-style haircuts, and they were wearing clothing appropriate for a warm climate," Bazbaz told the television network Televisa.
The mountains around Mexico City are colder, and Bazbaz said it was likely they were from the warmer, drug-plagued neighboring states of Michoacan or Guerrero.
In a statement, the federal Attorney General's Office said it was considering taking over investigations into the case, an additional indication that organized crime - a federal offense - was involved.
Mexico's drug cartels and criminal gangs have been slaying their rivals in increasingly large numbers, and publicly dumping their corpses, although not in the numbers seen on Friday.
On August 28, 12 decapitated bodies were found outside Merida, the capital of Yucatan state.
Investigators say three suspected killers detained in the Yucatan case belonged to the "Zetas," a group of hitmen for the Gulf drug cartel.
