At least eight people are missing after they were swept away by floods in the Mukaa area in Makueni County.
This follows heavy rains that pounded the region on Thursday night, officials said.
Police said the eight attempted to cross the Muuoni River, which was overflowing with water at around 10 pm.
Many other people were unable to cross and reach their homes as the river was overwhelmed by the floodwaters, police and locals said.
The victims were part of a larger group returning home after a meeting with First Lady Rachel Ruto in Kasarani, Nairobi.
On reaching Kavuthu Township, they ignored warnings that the river had swollen following heavy rains that had pounded the region for hours.
They were sitting on a log floating in the middle of the river after being overwhelmed by the raging waters as they tried to cross when they were swept.
Ongoing heavy rains and flooding – which are linked to the El Niño weather phenomenon – have killed at least 71 people and displaced more than 150,000 in Kenya, according to the Kenya Red Cross.
El Niño is caused by the Pacific Ocean warming and is linked to flooding, cyclones, drought, and wildfires.
Thirty-three out of 47 counties have been affected, but Makueni is among the most affected, alongside Wajir and Mandera.
Despite the widespread devastation, Kenya’s Deputy President Rigathi Gachagua on Wednesday said that the national government would not fund flood-response efforts.
The floods have killed more than 130 people in Kenya, Ethiopia and Somalia, according to the aid agency Oxfam.
Many factors contribute to flooding, but a warming atmosphere caused by climate change makes extreme rainfall more likely.
