Reports say a dam burst in Kenya on Wednesday night after heavy rain, causing “huge destruction” and killing at least 20 people.
The breach happened on farmland near the town of Solai, 190km north-west of the capital, Nairobi.
The Kenyan Red Cross says it has rescued some 40 people so far.
More than 2 000 people are said to have been left homeless. Local officials say the full extent of the damage is not yet clear.
Residents say many more people cannot be accounted for.
There are fears the death toll could rise as the search-and-rescue operation continues.
Reports say the Patel dam in Nakuru County broke its walls, and swept away hundreds of homes downstream.
Witnesses say they heard a loud bang before the waves swept through nearly 2km (of private farmland where many live and work.
“The water has caused huge destruction of both life and property. The extent of the damage has yet to be ascertained,” said Lee Kinyajui, governor of Nakuru county.
The Patel dam is one of three reservoirs owned by a large-scale farmer in the area.
Its walls are said to have caved in due to the high volumes of water following heavy rains that have been pounding the country.