Railway sources described it as a miraculous escape for other passengers as the train was moving slowly.
Six coaches have derailed of which two coaches and the engine are submerged in water.
22-year- Puran Singh from Cahinpur village of Purnia district died in the accident. His body has been sent to Khagaria hospital for post mortem.
One lady passenger who received a head injury is in a critical condition and has been admitted in the hospital same hospital. The injured people have been given first aid. The rest of the passengers have been sent to Katihar by another train.
The GRP escort rescued the driver and occupants of two coaches.
Five passenger trains have been cancelled and 15 long-distance trains, including the North-east Express, have been diverted.
Traffic restoration on main line will take a couple of hours.