A survivor, Ms Rhoda Atieno, told the Nation that before the crash, the bus crew had experienced mechanical problems throughout the journey.
Jaspa Ombati, the Regional Police Commander, said fatalities include five women, seven men and an infant.
At least 14 people were killed and dozens others injured in a grisly road crash involving Coast Bus at Migaa black spot on Nakuru-Eldoret highway on Tuesday morning.
The 5am horror that saw the long-distance bus roll and land in a ditch involved multiple vehicles, including a saloon car, according to local police, witnesses and Kenya Red Cross rescue teams.