The accident took place in Surkhet district, 650 km west of Kathmandu, when the passenger bus heading towards Birendranagar from Gumi village veered off 50 metre down the road.
Thirteen people were killed in the accident. All those injured in the accident have been admitted to a hospital in district headquarters Birendranagar.
The condition of five passenger is said to serious, according to the police.
The bus was completely damaged in the accident.