At least seven people were Monday morning killed in an accident between a lorry and a matatu on the Nakuru-Eldoret Highway.
There are fears the death toll may rise.
Five others were rushed to hospital with serious injuries, police said.
The incident happened at about 3.30 am and involved a 14-seater matatu that was headed for Nakuru and a truck moving in the opposite direction, police said.
Rift Valley regional police commander Tom Odera said the lorry driver is believed to have veered off his lane and collided with the oncoming matatu.
He said seven people died on the spot and at least five others were taken to hospital in critical condition.
The accident occurred at the Ngata stretch, and those injured were rushed to the Nakuru level 6 hospital, police and witnesses said.
Officials fear such accidents will rise in the rainy season ahead of the festivities.
