More than 10 villages in Bihar's Gopalganj district were flooded early on Sunday after the Gandak river overflowed its banks due to release of water from Nepal following heavy rains in the area, an official said.
The supporting embankments constructed to restrict the flow of river in case of flood threat were breached after Nepal released over two lakh cusecs of water in the river.
"Gandak river breached supporting embankments due to heavy pressure in the last 24 hours," an official of the state disaster management department told IANS.
A district official said the threat of flood looms large over dozens of other villages, creating panic among thousands of residents.
Hundreds of people fled their homes and the state government has asked those living in low lying areas to shift to safer places.
Rescue and relief operations have been intensified in the area. A team of the National Disaster Response Force has been rushed with motorboats to help those trapped in water, the official said.
In 2008, more than three million people were rendered homeless in Bihar when the river Kosi breached its bank upstream in Nepal and changed its course.