At least 30 people were feared dead when an overcrowded country-boat carrying over 50 passengers overturned in River Bagmati near Duba Ghat in Bihar's Sheohar district on Monday, official sources said.
The boat capsized midstream while sailing to the other side from Duba Ghat, possibly following sudden discharge of water from a barrage in upper Nepal, officials said.
About 20 passengers swam to safety, they said.
A search operation has been launched with the help of local divers.
Senior district officials are camping at the spot to oversee the rescue operation.