Forensic teams had working at the site since July 30, prosecutors said. Authorities were working to identify the remaining bodies.
The discovery came less than two months after a mass shooting at a street party in Irapuato left 12 people dead.
Guanajuato has suffered persistent violence in recent years as the powerful Jalisco New Generation Cartel battles the homegrown Santa Rosa de Lima organized crime group. The state recorded more than 1,500 homicides from January through July.
Organized crime groups frequently bury their victims in clandestine graves. The Mexican government’s current tally of disappeared is nearly 132,000.