Three women died after a lorry's brakes failed and rammed into them along Meru-Maua road.
The lorry loaded with sand is said to have been heading towards Maua when it lost control and crashed into the women fetching water.
Mr William Gitonga, an eyewitness, said: "I saw the lorry coming at high speed and rammed into a probox before before knocking down the three women."
Police arrived at the scene and helped in the rescue mission and controlling traffic. Pupils who were coming from athletics competitions nearby were also injured.