A natural stone quarry in Indonesia’s West Java province collapsed on several people who were working in it on Friday, killing at least 10 people and leaving six workers missing, officials said.

More than two dozen people were trapped in the rubble when the mine in Cirebon district collapsed, local police chief Sumarni said, and rescuers were able to pull a dozen injured people from the debris during a gruelling search effort.

“Authorities are still investigating the cause of the collapse, and we have been questioning the owner and workers of the quarry,” Sumarni said, adding that search and rescue operations were hampered by unstable soil that risked further landslides.