According to Mining News Pro - The provincial minister of mining, Dieudonne Apasa, said that the incident took place on Saturday afternoon when the torrential rains that have been pouring over the area for weeks softened the terrain so much that it started to crumble. 

Apasa said that two miners were rescued alive. Normally, these panners sell gold nuggets to local traders, who resell them to large foreign companies.

The news agency’s report states that a similar disaster killed 31 people just two months ago at an artisanal mine in Maniema, in the central-east region, while storm-caused landslides over the capital Kinshasa were blamed for at least 41 deaths at the end of November.

http://www.miningnewspro.com/en/News/458791/Two dozen people dead after landslide at DRC gold mine