Zacatecas Attorney General Francisco Murillo said authorities have so far found the bodies of 11 men and three women, but there could be more at the site in the municipality of Valparaiso.
"In some cases, the bodies are dismembered, some are bound and others are recent," he said at a news conference yesterday.
Federal and state security forces have been pursuing a criminal gang in the area where the mass grave was found.
Forensic experts were still working the scene in search of other bodies.
More From This Section
A mass grave with 18 bodies was found in June at Los Cabos, a beach resort in northwestern Mexico.
More than 177,000 people have been murdered and another 30,000 have been gone missing in Mexico since 2006, when the government deployed the military to fight organized crime.
Experts say the capture of the top drug cartel leaders has spawned numerous independent criminal groups that have moved beyond drug trafficking into robbery, kidnapping, extortion in areas they control.