Eight pupils from Kichare Primary School in Gwasi were seriously injured when their bus veered off the road and landed in a ditch near Ahero on Sunday evening.
An earth mover was brought to lift the bus so that the pupils could be rescued. Thirty-five others had minor injuries.
The headteacher of the school, Jackton Oyier, who was accompanying the pupils, was also injured. The eight were referred to Jaramogi Oginga Odinga Teaching and Referral Hospital in Kisumu from Ahero County Hospital.
The pupils were coming from the Nyanza regional music festival at Lions High School in Kisumu.
Eyewitnesses and some of the pupils said the driver of the bus belonging to Tonga Boys Secondary School in Gwasi fled soon after the 5.30pm accident.
"He was speeding on the wrong side of the road when the bus hit a bump, swerved off the road and crashed into a ditch," said a motorcycle rider who was behind the bus and helped rescue the learners.
Regional traffic boss Andrew Naibei said officers were pursuing the driver.
He added that investigations were on to establish the cause of the accident.