The incident came less than 24 hours after at least 39 pilgrims were killed when an overcrowded bus taking them from India to a Hindu festival in southern Nepal fell into a canal.
Police said Monday’s deaths occurred when the night-bus fell 200 metres (650 feet) down a cliff after the driver was thought to have fallen asleep.
“A passenger bus on its way to Kathmandu from Katari slipped off the road at Krishnabhir and fell into the river,” police sub-inspector Narayan Prasad Chalise said.
“We recovered six bodies from the accident site and three seriously injured died in hospital in Kathmandu. Another 17 people are injured and are undergoing treatment.”
Accidents are relatively common on Nepal’s highways because of poor roads, badly maintained vehicles and reckless driving.