Eleven passengers suffered minor injuries when 14 coaches of the Guwahati-bound Rajdhani Express derailed at Amba halt between Kharik and Naugachia railway stations in Bihar on Tuesday.
Rail traffic has been disrupted on the section due to the derailment.
East Central Railway Chief Public Relations Officer Dilip Kumar said the derailment took place at village Amba around 6:30 am when the train was on way to Guwahati from New Delhi.
The driver of the train applied emergency brakes after hearing the sound of an explosion on the tracks, which apparently led to the derailment, Kumar said.
However, the exact cause was still to be ascertained, the CPRO said, adding that the possibility of sabotage was also being examined.
Police has denied suggestions that it was the handiwork of Maoists.
Kumar said a statutory inquiry by the Commissioner of Railway Safety, Eastern Region, R P Yadav, has been ordered into the cause of the derailment.
The injured passengers were administered first-aid on the spot, Kumar said adding teams of doctors from Katihar and Barauni soon reached the spot to provide medical assistance.
A special train comprising 17 coaches arrived at Naugachia to transport around 940 passengers of the Rajdhani Express to Katihar Railway Station for facilitating their onward journey, he said.
Special arrangements were made to provide food to the passengers, he said.
Routes of several trains, including Mahanand Express, were diverted as rail traffic was disrupted on the Khagaria-Naugachia section following the derailment. Cranes were engaged in removing the derailed coaches for ensuring traffic in the section.
Four pairs of passenger trains, besides up and down Tata-Katihar link express were cancelled because of the accident, Kumar said, adding ECR officials were camping on the spot.
A relief train has also reached the derailment site, he said.
Railways have set up help ine numbers in Delhi for the convenience of the passengers and their families. The New Delhi railway helpline numbers are 011-23341074, 011-23341072 and Old Delhi - 011-23967332, 011-23962389.