The fire reportedly erupted at 2.35 a.m. in the vestibule connecting S-2 and S-3 coaches and quickly spread to the S-4 coach, catching the sleeping passengers unawares, the Western Railway said.
The train had left Mumbai and was headed to Dehradun in Uttarakhand.
Ten passengers who inhaled toxic fumes were given first aid by railway accident relief vans and taken to hospitals in Dahanu and Gholwad, around 145 km north of Mumbai, said an official.
Five of the passengers who died were identified as Deepika Shah (65), Dev Shankar Upadhyay (48), Surendra Shah (68), Nasir Khan Ahmed Khan Pathan (50) and Feroz Khan (38).
It was the second railway disaster of its kind since Dec 28 when 26 people died after the Nanded-Bangalore Express caught fire in Andhra Pradesh.
A railway official said the Wednesday fire was noticed in the moving train by a gateman between Dahanu Road and Gholvad.
He alerted the station master of Gholvad who in turn informed the driver and the train was stopped.
The official said that there may have been a far worse disaster but for the gateman's alert.
The fire was controlled shortly after the train halted near the Gholwad station.
Railway Minister Mallikarjun Kharge expressed anguish over the tragedy and announced an ex-gratia of Rs.500,000 to the families of the dead.
The Railway Board ordered an inquiry into the incident and related aspects of the fire.
Six coaches of the train were detached and five new coaches were added before the train left the site some three hours after the tragedy.
Train services hit on the route were restored by 6.40 a.m.
--IANS (Posted on 08-01-2014)