Six people died on Saturday in a crash on Kapsabet-Chemelil road, Nandi County, after a matatu veered off the road and rolled several times.
County Police Commander Patrick Wambani said preliminary investigations indicated that the driver lost control after the vehicle's brakes failed.
Mr Wambani said five people died at the scene in Chebarus and one en route to hospital.
Five of the victims were among people who had hired the vehicle to ferry to Bomet County for a wedding while the sixth victim had been standing by the road when she was hit.
At least seven people were taken to nearby hospitals, including Moi and Kapsabet referral, with critical injuries.
On December 21, 11 people died when a matatu and a petrol trailer collided at Kaburengu on Webuye-Eldoret highway in Kakamega County.
Bungoma County Police Commander, Francis Sang, said reports indicated that the accident took place after the brakes of the trailer failed.
Following the high number of accident deaths in December last year, and in order to generally reduce these cases, the Interior ministry carried out a crackdown from November for the reinforcement of Michuki rules.
In December 2017 alone, at least 330 people died in road crashes.
The regulations were published in a Kenya Gazette notice in September 2003 by the then minister of Transport, the late John Michuki.
The highlights are for every public service vehicle to be fitted with a speed governor that caps speed at 80 kilometres per hour and have seatbelts for all passengers and a defined passenger capacity to prevent overloading.
Drivers are also required to display their photos prominently in the matatu to curb “squad” driving.
Interior Cabinet Secretary Fred Matiang'i said police and relevant bodies, including the National Transport and Safety Authority, will not relent until sanity is restored.