The bound and gagged bodies of 26 men were found in the heart of Guadalajara, a sign that full-scale war between drug cartels may have come to the picturesque western city which hosted last month's Pan American Games.
The state prosecutor's office said the men were found before dawn yesterday in two vans and a pick-up truck abandoned near the Millennium Arches, one of the most recognisable landmarks in Mexico's second-largest city.
Best known as the home of mariachi music and tequila, Guadalajara also sits on the main highway running from the methamphetamine-producing state of Michoacan north toward the Pacific Coast state of Sinaloa.
In recent months, security officials and analysts have expressed concern that the city could become a target for the Zetas drug cartel, which has been using paramilitary-style tactics and headline-grabbing atrocities in a national push to grab territory from older organised crime groups.
"These acts of barbarism show how the war between cartels, and crime, is getting more brutal," Guadalajara's mayor, Jorge Aristoteles Sandoval, told reporters.
A message was found with the bodies in one of the vehicles, said Luis Carlos Najera, public security secretary for the state of Jalisco. He gave no details, but Mexican cartels frequently leave threatening messages with the bodies of their victims as a way of sowing fear and taking credit for their actions.
The 26 bodies were found about a mile from the Expo Guadalajara events centre, the site of both Pan Am Games events and the Guadalajara International Book Fair, which opens on Saturday and describes itself as the world's most important Spanish-language book fair. The fair's website said it was expecting more than 600,000 visitors from around the world.
Crime in this colonial city of some 1.5 million people was historically dominated by the powerful Sinaloa cartel, but the group's tight grip was shattered by the death of its regional commander, Ignacio "Nacho" Coronel, in a shoot-out with federal police in July 2010.
Guadalajara's murder rate then soared as factions of the cartel known as the New Generation and the Resistance battled to control Coronel's territory and assets. Street battles have left hundreds dead in the city and surrounding areas.
Killings slowed to a trickle during the October 15-30 Pan American Games, which brought a massive influx of police and soldiers. Law-enforcement officials and analysts said they were nonetheless concerned that a Zetas onslaught could be imminent.
Yesterday's massacre bears the hallmarks of the Zetas, perhaps working in concert with the Resistance, said Samuel Logan, director of Southern Pulse, a risk-analysis firm specialising in Latin American organised crime.
If the Zetas turn out to be responsible, the Guadalajara attack may be part of a sustained offensive against Sinaloa, he said.
On Wednesday, 17 bodies were found burned in two pick-up trucks in a strikingly similar attack in Sinaloa, the home state of the eponymous cartel. Twelve of the bodies were in the back of one truck, some of them handcuffed and wearing bulletproof vests.
"I think the location is significant, that points in the direction of the Zetas," Mr Logan said, although he cautioned that another cartel may well turn out to be have been responsible.
"Maybe the Zetas pushing into Guadalajara creates the next major battlefront... If it was the Zetas, they're going to continue pushing."
Responding to a reporter's question, Mr Najera told the Televisa television network that he believed the recent calm in Guadalajara was the result of an increase in security and not because drug cartels had struck a truce with each other during the games.
He declined to comment on the possible motives for the killings, saying only that investigators had "various hypotheses".Reuse content