Some 45 passengers were travelling in the bus when the incident occurred early morning in Dadelhura district on the Dhangadhi-Bhimdutta Highway, Dadeldhura DSP Keshab Bohara said.
Sixteen critically injured persons have been shifted to zonal hospital in Dhangadhi. Others are receiving treatment at Dadeldhura, the Himalayan Times newspaper reported.
The cause of the accident is not known yet. The road on which the accident took place is narrow with hairpin bends and the visibility was poor because of morning fog.