Illegal gold mining is getting worse in South Africa, according to rescuers, who hauled a record number of corpses from abandoned mines this year.

“It’s spiralling out of control,” Christo de Klerk, chief executive officer of Mines Rescue Services, told reporters in Johannesburg on Tuesday. “It’s getting worse and worse and worse.”

The company’s main job is to rescue workers at operating mines, but more time is being spent at accidents in abandoned shafts, De Klerk said.

This year, 24 bodies have been recovered by Mines Rescue Services, the most since records began in 2009. In 2015 and 2014, the death toll was 22 and 3, respectively.

It’s only the “tip of the iceberg” De Klerk said, estimating that they find no more than 10 percent of the dead.

South Africa is home to thousands of interlinked abandoned mines stretching for hundreds of kilometres after more than 130 years of mining gold. Impoverished people, mostly immigrants from Lesotho, Zimbabwe and Mozambique, scour the mines for the little gold that remains. They often start by removing gold-rich pillars left behind to bolster the structure of the mine, causing rockfalls and leaking gas, De Klerk said.

Gold reached an all-time high of about R659 000 ($48 700) a kilogram in late June, boosted by the weak local currency and rising demand for precious metals.

At illegal mines, gangs are becoming increasingly sophisticated, using explosives, power generators and processing materials to assist their mining while bringing food to sustain them for months underground at a time, according to De Klerk. After refining the gold to 85-90 percent purity, it is sold to organised crime syndicates, he said.