The accident occurred when a matatu driver lost control of his vehicle that was part of a wedding convoy to Litein in Kericho.
The 14 passengers had boarded the matatu at Chomisia in Nandi central subcounty to escort a bride to Kericho.
County police commander Patrick Wambani said the matatu veered off towards the opposite lane and rolled several times.
Four passengers, including the driver, died on the spot, while the fitfth person was a female pedestrian who was run over.
“The sixth person died while on his way to Moi Teaching and Referral Hospital in Eldoret,” Wambani said.
Nandi Kenya Red Cross disaster coordinator Josephat Sirma said his team of volunteers were the first on site and managed to pull out eight people, but in critical condition.
The matatu was ferrying 14 passengers and a child who is yet to be located.
The accident happened at Corner Nyanya in Chebarus location near the Chepsangor black spot.
County commissioner Mohammed Barre who visited the site asked drivers to exercise caution.