The accident occurred at Kikima area at the border of Machakos and Makueni counties at about 3 am.
Bodies of five were recovered immediately after the accident that occurred at around 4 am.
Police said all those killed are members of the same family or distant relatives because they were going back home in Tala after a bride price ceremony in Makueni.
“The area where the accident occurred is a black spot where many accidents have occurred in the past. We had a similar one of people from a bride price sometimes back,” a police officer in the region said.
Cases of road accidents in the country are on a steady rise in recent weeks despite assurances from police and the National Transport Safety Authority (NTSA) on enhanced enforcement of traffic regulations.