The collapse at the Luhihi mine in Kabare territory took place late Wednesday and was caused by “a natural disaster caused by climate change,” the rebel-appointed vice-governor of South Kivu, Dunia Masumbuko Bwenge, told The Associated Press. Floods and landslides are frequent in this area east of South Kivu, which borders Rwanda. In 2023, at least 400 people died in flash floods in Kalehe territory. Bwenge said that because Luhihi is an artisanal mine, there were also several irregularities and workers did not follow safety regulations.

Jean-Jacques Purusi, who was governor of South Kivu before M23 took over, confirmed there had been a collapse at the mine. He said the collapse killed at least six people and many bodies caught under the rubbles have not been retrieved yet. Bwenge, the rebel-appointed vice governor, said at least 10 people had been killed. The decades-long conflict in the region escalated in January, when the M23 rebels advanced and seized the strategic city of Goma in North Kivu province, followed by Bukavu in February.

M23 is one of about 100 armed groups that have been vying for a foothold in mineral-rich eastern Congo near the border with Rwanda, in a conflict that has created one of the world’s most significant humanitarian crises. More than 7 million people have been displaced. The rebels are supported by about 4,000 troops from neighboring Rwanda, according to U.N. experts, and at times have vowed to march as far as Congo’s capital, Kinshasa, about 1,600 kilometers (1,000 miles) to the east.