Fourteen dismembered bodies have been discovered in a lorry in north-eastern Mexico, local officials say.
The vehicle was parked outside the mayor's office in Ciudad Mante, in Tamaulipas state.
Reports say gang-related messages were found on the blankets covering 11 men and three women.
About 50,000 people have died in drug-related violence in Mexico since 2006, when President Felipe Calderon deployed the army to combat the cartels.
A man was reported to have abandoned the vehicle with the bodies, but very few details of the gruesome case are known, the authorities say.
There are no clear indications as to which of the powerful criminal groups in Tamaulipas was responsible for the killings, and none of the victims have been identified.
There are two main cartels operating in this region of Mexico - the vast criminal network known as los Zetas, and their main rivals, the Gulf Cartel.
The incident was first reported via Twitter and other social networking sites, which are increasingly becoming the first place via which such information reaches the public domain, the BBC's Will Grant in Tamaulipas reports.
The bodies were discovered just a day after the frontrunner in Mexico's presidential election, Enrique Pena Nieto, visited the state, promising to reduce the murder rate if elected, our correspondent says.
Last month, 49 beheaded and mutilated corpses were found dumped in the northern city of Monterrey.