There were around 80 people in the boat when the accident took place late Sunday near Dallupur bank, about 125 km from Patna. At least 15 people were still missing, a police official said.
The passengers, all of them poor labourers, were returning after plucking maize.
"Prima-facie it appears the accident took place because of over-loading," the police official said.
A district official said: "The boat could ferry 35 people, but at the time of the accident the boat had people more than twice its capacity."
Rescue and search operations are on, the official added. The Bihar government has ordered a probe into the accident and announced a compensation of Rs.1 lakh each for the kin of the dead.
Published 11 October 2010, 04:01 IST