The victims, between the ages of 25 and 30, were eating at the restaurant when gunmen entered and opened fire without warning, according to a report filed by local prosecutors.

A prosecution source told local media that the shooting appeared to be linked to organized crime.

Some 25,000 people have been killed in Mexico since December 2006, most of whom appeared to have been victims of assassinations at the hands of the country's drug cartels after President Felipe Calderon launched a military crackdown on organized crime.

The latest killings came one day after eight human heads were found in four separate places near roadsides outside the northern Mexico city of Durango.

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