Experts said that people died due to asphyxiation.
The fire is believed to have erupted in one bogie and quickly spread to two other bogies, catching the passengers in their sleep around 2.30 a.m. Wednesday, a Western Railway official spokesperson said.
"The fire was noticed on the speeding train by a level-crossing gateman who alerted the guard. The guard informed the driver and the train was stopped. The gateman did a commendable job and averted a major disaster," the spokesperson said.
According to preliminary information, the fire broke out in S-3 coach and quickly spread to the other adjoining coaches as the train hurtled to its destination.
Helpline numbers for the Dehradhun express fire are 022-23011853 and 022-23007388.
Two of the victims identified are Dipika Shah of Ghatkopar and Devshankar Upadhyay of Borivli, while the identities of the others are being ascertained.
The fire was brought under control shortly after the train was brought to a halt at Gholwad station, around 145 km from north of Mumbai on the Maharasthra-Gujarat border.
Minister orders probe
Railway minister Mallikarjuna Kharge has ordered a probe into the fire incident. the ministry has also announced compensation of Rs 5 lakhs for victims' families.
Accident relief vans have been sent from Mumbai and Gujarat to assist in the relief operations and the injured have been admitted to hospitals in Dahanu and Gholwad, the official said.
Top officials, including the divisional railway manager, have rushed to the tragedy site and are supervising the relief operations.