At least three of the bodies had bullet wounds. The others appear to have been beaten to death.
Investigations into the case are continuing, but the style of the killings suggested the involvement of drug gangs.
An employee of the state prosecutor's office who was not authorized to be quoted by name said the bodies were found on a street in the city of Gomez Palacio on Tuesday.
More than 10,800 people have been killed by drug violence since President Felipe Calderon launched a nationwide crackdown on organized crime in late 2006.