Congolese authorities say the toll could rise as rescuers sift through mud and rubble of collapsed homes.

The disaster took place on Sunday along the Congo River in the town of Lisal in Mongala province, according to Matthieu Mole, president of the civil society organisation Forces Vives. The victims lived in homes that were built at the foot of a mountain.

“A torrential downpour caused a lot of damage, including a landslide that swallowed up several houses,” he said on Sunday. “The toll is still provisional as bodies are still under the rubble.”

Governor Cesar Limbaya Mbangisa said machinery was desperately needed to help clear away the debris and try to save any survivors. The governor offered his condolences to the victims’ families and decreed three days of mourning throughout the province.

Poverty and poor infrastructure have made communities in such areas more vulnerable to extreme weather such as heavy rains, which are becoming more frequent and intense in Africa due to climate change, United Nations climate experts said.

In April, President Felix Tshisekedi declared a day of national mourning after 16 people died in multiple landslides in the Lubero territory of North Kivu province.