Four people aboard perished in a grisly accident on the Olenguruone-Bomet road on Tuesday evening.
One died on the spot and three others succumbed to injuries while receiving treatment at Tenwek Mission Hospital.
The accident that occurred at Mugango area also left nine people injured and they were admitted to the same facility.
Bomet Central Sub County police boss Geoffrey Walumbe said the driver of the 14-seater matatu was headed towards Bomet when it veered off the road.
According to him, the vehicle rolled several times before landing in a ditch.
Mr. Walumbe said upon interrogation, the driver claimed that the matatu brakes had failed after a collision with a boda boda that was headed in the opposite direction.
The bodies of the deceased were taken to the Longisa County Referral Hospital mortuary.