MONTERREY, Mexico – The Colombian-style music group was playing at a ranch in northern Mexico when at least 10 gunmen entered the warehouse where the private party was being held and forced the musicians and several of their crew members into waiting vehicles, a survivor of the attack told authorities.

Nuevo Leon state security spokesman Jorge Domene said the survivor, a member of the Kombo Kolombia band, told police the 18 were blindfolded and driven on dirt roads until they stopped. He then heard the assailants ask fellow band members if they belonged to a drug cartel, shots were fired and the bodies were dumped into a well.

Domene said the survivor was able to reach a nearby ranch and get help. He wouldn’t give details on how the man was able to escape.

The man later led authorities to the well where searchers found several bodies, Domene said.By Monday afternoon, 12 bodies had been pulled from the well in the town of Mina, about 140 miles from Laredo, Texas, Domene said. The bodies recovered showed signs of torture, said a forensic official.

Authorities initially said 16 members of the band Kombo Kolombia and four crew members were reported missing early Friday after playing at a private party attended by about 50 people in the town of Hidalgo north of Monterrey. But Domene said Monday 18 band members had gone missing.