The accident occurred in Sunsari, 200km south-east of Kathmandu
Rescuers are still searching for passengers from a ferry that capsized in eastern Nepal on Sunday.
Three bodies have been found and 17 people rescued but the number missing is unknown - reports said the ferry was carrying between 20 and 50 people.
The accident occurred in Sunsari district, about 200km (125 miles) south-east of the capital, Kathmandu.
Police said poor visibility due to fog had caused the boat to strike an object and overturn.
Sunsari district police inspector Dambar Tamang told the BBC there had been no contact with the boatmen and their fate was unknown.
A lack of roads in Nepal means that boats are a common form of transport
At least five people have been reported missing by relatives.
Local boatmen have joined teams from the police and the army in the rescue.
Police said a third body was reported to have been found but this has not yet been verified.
After the incident the administration in Sunsari said it was clamping down on any boats found to be over capacity.
The BBC's Ishwar Rauniyar in Kathmandu says there are rules in place on how many passengers boats can carry but they are often ignored by owners.
Our correspondent says boat travel has become more necessary after roads were damaged following the collapse in September of the Saptakoshi embankment near the Indian border.
The collapse caused massive flood damage to parts of Nepal and India's Bihar state.