At least seven people were killed on the spot after a lorry carrying gravel (kokoto) rammed into roadside traders and pedestrians at Kaburengu market in Lugari, Kakamega County.
14 other people were injured and rushed to Webuye Referral Hospital.
The driver of the lorry is said to be among the casualties. A bodaboda operator also died as the lorry hit him before ramming into a matatu which was parked by the roadside.
Kakamega County Police Commander James Ngetich, confirming the 2 pm incident, said the lorry was headed to Webuye before it lost control and hit traders and pedestrians by the roadside.
Mr Ngetich added that investigations have commenced to establish what caused the driver to lose control of the vehicle.
Unconfirmed reports have indicated that the death toll might have risen to 10 but official police reports revealed 7 casualties.
Bodies of the deceased were ferried to Webuye sub-county hospital mortuary.