The dismembered remains of 14 men were found stuffed inside a minivan left near the town hall of a Mexican city that is often a flashpoint for the country's drug war.
The remains were found in Nuevo Laredo's business district just after sunrise packed inside 10 black plastic bags found in the vehicle, officials said on Tuesday.
A threatening message was found with the bodies.
Nuevo Laredo, adjacent to the US city of Laredo, is a stronghold for the Mexican drug cartel the Zetas.
More than 50,000 people have been killed since President Felipe Calderon began a campaign to curb drug trafficking in 2006.
Much of that violence has been focused on border towns that serve as transit points for illicit drugs.