Ten bodies have been fished out so far by divers, official sources said.
Meanwhile, rescue operations were halted due to bad weather and poor light conditions. The operations will now begin tomorrow morning.
The bus has been taken out of the canal.
Sources said the ten deceased were identified as Manju 35, Jaiprakash, 10 Yogendra 18, Bhikam Singh, 35, Arar Devi, 50, Ganga Devi, 50, Gajendra , 26, Rajwati, 35, Chote Lal, 14 and Kishan Pal, 28. They belonged to Hirnaut, Ramghat, Dinapur, Bhikampur and nearby villages.
About 70 people were travelling aboard the bus when the accident happened at Nangla Beni village at 1530 hrs, sources said.
The bus driver apparently lost control of the vehicle since it was raining and the road had turned slippery.
Some of the passengers, however, swam to safety.
The accident site is 50 km from the district headquarters.
Meanwhile, state Chief Minister Mulayam Singh Yadav announced an ex-gratia of Rs one lakh to the family members of the deceased in the accident.
Sources said there was no information about the exact number of missing persons.