The accident occurred in Makuyu at about 6am, near where nine people were killed in another mishap on Thursday last week.
“One person died on the spot while three others succumbed to injuries in hospital,” Traffic Commandant Samuel Kimaru told Capital FM News on telephone.
“There was a head-on collision between a matatu and a light truck,” he said and urged motorists to be cautious on the road, particularly during the rainy season.
Witnesses and survivors of the accident told police the mishap occurred when the matatu tried to overtake another vehicle.
Passengers trapped in wreckages of the two vehicles were rescued by Kenya Red Cross volunteers.
On Thursday last week, nine people died while several others were injured after a matatu collided with a light truck on the highway.
Among the dead were the drivers of the matatu and the truck who perished on the spot as well as seven passengers in the matatu.
“I don’t know for how long we will sing the song of cautious driving, because majority of these accidents are caused by human error,” Kimaru said at the time.
Statistics released by the Traffic department two weeks ago show that 904 people have died in road accidents since the beginning of this year.
They include 395 pedestrians, 79 drivers and 272 passengers.