Mexican authorities have found 45 bags containing human remains in a ravine outside the western city of Guadalajara.
Officials were searching for seven young call centre workers, who had been reported missing last week, when they found the bodies.
The remains include men and women, and the number of bodies is not yet known.
The search is expected to continue for several days because of difficult terrain and poor lighting.
The state prosecutor’s office for the western state of Jalisco said in a statement that, following a tip-off in the search for the seven people, they had begun searching at the Mirador del Bosque ravine where they found the bags that included body parts.
Firefighters and civil defence were working with police and a helicopter crew to recover the remains.
The first bag was found on Tuesday, but because of the difficult terrain and lack of sunlight, the investigation resumed on Wednesday and will continue until all remains are located, the prosecutor’s office said.
Officials said they would continue working to determine the number of dead bodies, who they were, and their causes of death.
It added that it would continue trying to establish the whereabouts of the seven people reported as missing.
Although it has not yet been established how the bodies ended up in the ravine, crimes of disappearance are relatively common in Mexico.
More than 100,000 people are missing, government figures suggest, with many being victims of organised crime. Perpetrators are rarely punished.
Government data shows that many disappearances have occurred since 2007, when then-President Felipe Calderón launched his “war on drugs”.
Three quarters of those reported missing were men and one fifth were under the age of 18 at the time of their disappearance.
Relatives of the disappeared say that the government is not doing enough to find them, and that officials are indifferent when they report their loved ones as missing.
The United Nations has called it “a human tragedy of enormous proportions”.
Jalisco is the heartland of a violent drug war, and some of the most powerful groups operating there include the Jalisco New Generation cartel (CJNG), and their rival, Nueva Plaza, which split from the CJNG in 2017, sparking violence across Guadalajara, the capital of Jalisco state.