At least 55 people were feared killed when an overcrowded boat capsized in Kosi river in Saharsa district of Bihar on Tuesday night.
According to reports reaching capital Patna, the boat was carrying 80 people and only 25 of them managed to either swim to safety or were rescued.
Rescue teams have not yet recovered any bodies.
This is the first major mishap in flood-prone northern Bihar in this year's monsoon.
Saharsa's Superintendent of Police Ajitabh Kumar and Sub-divisional Officer Naim Akhtar are supervising rescue efforts.
Earlier report: Thirty feared dead in Bihar boat mishap