Pupils had travelled more than 600km and were just 3km away from their destination when crash occured.
The accident occured on Saturday night when the school bus collided head-on with the truck and plunged into River Tyaa.
Ten pupils have died and 27 others seriously injured following a crash involving a school bus and a truck near Mwingi town on Saturday night.
The bus was travelling from Mombasa when the accident occurred some minutes to midnight, just 3km before reaching its destination after having covered more 600km.
Parents of pupils from St Gabriel Bearding Primary School in Mwingi, which is run by the Kitui Catholic Diocese, were waiting just a few kilometres to receive them when their lives were cut short.
Kitui Central OCPD Muthuri Mwongera, who coordinated rescue efforts, said eight pupils died on the spot when the bus rolled several times after colliding with an oncoming truck.
Six victims were referred to Kenyatta National Hospital for specialized treatment after sustaining multiple fractures, but one pupil died on the way.
Mr Mwongera said the two vehicles collided at a narrow bridge when the bus was rammed on the right side by the truck.
The school bus then rolled several times before plunging into the dry Kanginga River bed, which feeds into the Tyaa River.
“Preliminary investigations show the bus was hit on the right-hand side and the pupils that died were seated on that side. It veered off the road on impact and rolled until it landed into the river,” Mr Mwongera told the Nation.
He said the bus, which had been hired from another school was carrying 39 pupils, three teachers, a matron and the driver and that his officers were liaising with Mwingi Level Four Hospital where the injured were taken to account for all passengers.
Police have arrested the driver of the truck, who drove off from the accident scene heading to Nairobi. Police officers caught up with him 15km from the accident scene.
“We have put him in custody and will be arraigned tomorrow to face charges of causing death by dangerous driving,” said Mr Mwongera, adding the driver did not stop to help in rescue efforts.
Following the accident, Kitui Governor Charity Ngilu condoled the families that lost children in the tragic crash.
"I want to call upon everyone to pray for the parents to be strong enough to bear with this tremendous loss. Let's all pray for the souls of the little angels to rest in peace. Poleni sana," Ms Ngilu said.