Some of the injured receive treatment in a Kathmandu hospital
A crowded bus has veered off a highway in southern Nepal, killing at least 22 people, most of them schoolchildren, police have said.
The bus, which was returning from a picnic, went off the road near Mukundapur, some 200km (125 miles) south-west of the capital Kathmandu.
At least 57 more people were hurt and police fear the death toll could rise.
Road accidents are common in Nepal and claim hundreds of lives every year. There are no speed limits on highways.
Police officers in the Chitwan area told the BBC the bus was one of two ferrying a large party of children and teachers back from a school picnic late on Thursday night.
Travelling along the country's main highway, the bus fell off a bridge, plunging 25 metres into a river.
Most of the injured are being treated in the nearby town of Bharatpur, where the school is, but some have been flown to the capital.
The police said the driver had escaped and was missing.
They said the two buses appeared to have been racing each other.
The BBC's Charles Haviland in Kathmandu says fatal road accidents are grimly common in Nepal, not just in the mountains but, as here, in the plains too.
The standard of driving is poor and few rules of the road are observed, he says.