Authorities say police found the mutilated bodies of 14 men in a minivan abandoned in the downtown area of the border city of Nuevo Laredo.
Tamaulipas state prosecutors say in a statement that the bodies were inside plastic bags.
Prosecutors say officers also found a message signed by a criminal group, but authorities wouldn't identify the group or release the content of the note.
Prosecutors say all the victims were between the ages of 30 and 35, but they gave no other details. The bodies were found on Tuesday.
Nuevo Laredo, across the border from Laredo, Texas, is a stronghold of the Zetas drug cartel. It has been the scene of vicious turf battles between the Zetas its former ally, the Gulf cartel.