JAKARTA: An illegal gold mine in Indonesia's Sulawesi island collapsed on nearly two dozen people working inside, killing three and leaving another five missing, officials said Thursday.

Survivors estimated about 23 people were trapped in the rubble when the mine in Central Sulawesi province's Parigi Moutong district collapsed late Wednesday due to unstable soil, said Andrias Hendrik Johannes, who heads the local search and rescue agency.

Rescuers were able to pull 15 people from the debris and recover the bodies of three women during a grueling search effort, he said.

Police, emergency personnel, soldiers and volunteers were all taking part in the efforts to find those still missing, though efforts were being hampered by the remote location of the mine and the unstable soil that risked further slides, he said.

Video from the scene showed rescuers struggling to bring out a body bag from a ravine inundated by water.

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

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

Indonesia accounts for about 3% of world gold production. Most of that comes from the Grasberg mine in Papua province, said to have $40 billion in reserves and up to 20,000 workers.

But small, often unauthorized mining is on the rise in many parts of Asia and Africa. A study by the Intergovernmental Forum on Mining, Minerals, Metals and Sustainable Development found the number of people engaged in such mining had risen to over 40 million, up from 30 million in 2014 and 6 million in 1993.