The bodies of five miners have been recovered from the Hillo artisanal mine, and another three people were unaccounted for, regional commissioner Paul Rotich told Reuters by telephone late on Friday.
"Reports from rescuers, police and our chiefs suggest at (least) eight casual miners were inside the mining ground when the walls collapsed and buried them alive," Rotich said
Two injured miners were taken to hospital, Kenyan broadcaster NTV reported on Saturday morning.
"The place caved in because of the rains," Marsabit county commissioner David Saruni told NTV.
Hundreds of people have been killed in floods and landslides across the country following weeks of torrential rains.
Mining had continued despite authorities closing the mine near the Ethiopian border in March, after several people were killed in clashes between local communities over access to the area, Citizen TV reported.