Four people were on Friday in an accident involving a private car along Kericho-Awasi road.
One passenger survived the accident and is admitted to the hospital with serious injuries, police said.
The accident occurred in the Pala area when a driver of a Nissan Vanette car lost control and veered off the road.
Police said the car landed in a ditch, killing the four on the spot. The dead included the car's male driver, another male passenger, and two female passengers.
The survivor had a fractured left hand, police said.
The police arrived at the scene and helped to move the bodies to Ortho mortuary.
The car was towed to a local police station pending further investigations.
Police said the accident is under probe. It comes in the wake of increased fatal accidents in the past week that have claimed up to 20 lives.
Seven were killed on the Narok-Mai Mahiu road, four in Mariakani, Kilifi County, in the latest incidents.
Many others are nursing wounds following the accidents.
More than 4,000 Kenyans are killed annually in accidents in the country, which also leave thousands with serious injuries and with negative effects on families.
