At least three bodies out of eight missing persons have been recovered in a search and rescue mission in Mukaa area in Makueni County.
The victims were part of a larger group returning home after a meeting with First Lady Rachel Ruto in Kasarani, Nairobi.
The search for more bodies is ongoing, officials said Friday afternoon.
The tragedy 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.
Kenya Red Cross Makueni County officials said they had deployed a rescue and search team to the area.
Floods have killed more than 70 people and displaced many in the past weeks.
The meteorological department has warned of more rains in the coming days. Some 33 out of 47 counties have been affected, but Makueni is one of the most affected.
So far, at least 16 people in Makueni have died as a result of the ongoing Elnino rains, according to a report from Red Cross and the County Strategic Unit.
Kavuthu Chief Norman Musyoki urged people to be cautious during the rainy season to avert any tragedy.
