Rescue workers in Zambia have pulled out the first survivor of a December 1 landslide that inundated an open-pit copper mine and trapped at least 25 people working there, the disaster management unit said on Wednesday.

The rescue team also retrieved one body which had yet to be identified, the Disaster Management and Mitigation Unit said in a statement posted on Facebook.

Zambia’s President Hakainde Hichilema said on Tuesday he was still hopeful that the trapped miners, who were working there without a permit, were still alive, as rescue efforts continued.

It was still not clear how many miners had been trapped but mines minister Paul Kabuswe said 25 families had so far come forward to claim missing relatives who were working when the accident happened.

Rescue workers, including military personnel and others from large-scale mining companies, were being cautious due to soft ground, slowing down the operation.