According to eyewitnesses, the overcrowded boat was returning from a kite flying festival,
organised as part of Makar Sankranti by the state Tourism Department, when the incident took place around 6 p.m.
Rescue operations were hampered since it was already dark by the time. Six of the eight people rescued were pulled out from the river by the National Disaster Response Force, a team of which was deployed for the rescue operations.
Patna District Magistrate Sanjay Agarwal and district police officials are camping at the site.
Bihar Chief Minister Nitish Kumar has ordered a probe into the incident.
The state government also announced an ex-gratia of Rs 4 lakh to the next of the kin of the victims.