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 Regency collapsed, local police chief Sumarni said, and rescuers were able to pull a dozen injured people from the debris during a grueling search effort.

“Authorities are still investigating the cause of the collapse, and we have been questioning the owner and workers of the quarry,” said Sumarni, who like many Indonesians, uses a single name.

She said police, emergency personnel, soldiers, and volunteers were trying to locate any remaining workers, supported by five excavators, but were hampered by unstable soil that risked further slides.

The search was suspended Friday as darkness fell and will be resumed early Saturday for those reported still buried under the rubble, along with three excavators and six trucks, said the National Disaster Mitigation Agency’s spokesperson, Abdul Muhari, in a statement.

He said that as of Friday afternoon, rescuers have retrieved 10 bodies, while six people were hospitalized with serious injuries.

West Java Governor Dedi Mulyadi said in a video statement on Instagram that he had visited and identified the vulnerability of collapse at the mine, located at Gunung Kuda mining site in Cipanas village, before he was elected.

“I saw that C-grade mining was very dangerous; it did not meet the safety standard elements for its workers," Mulyadi said, adding that at that time, "I didn’t have any capacity to stop it.”

On Friday, Mulyadi said that he had taken firm action to close the mine and four other similar mines in West Java that are considered to be endangering the environment and lives.

A video showed rescuers struggling to bring out a body bag from a devastated area.

Illegal or informal mining operations are commonplace in Indonesia, providing a tenuous livelihood to those who labor in conditions with a high risk of injury or death.

Landslides, flooding, and collapses of tunnels are just some of the hazards in such mining. Much of the processing of sand, rocks, or gold ore involves the use of highly toxic mercury and cyanide by workers using little or no protection.

Last year, a landslide triggered by torrential rains struck an unauthorized gold mining operation on Indonesia’s Sumatra island, killing at least 15 people.