MUMBAI, India -- Fire and smoke engulfed three cars of an Indian passenger train early Wednesday, killing nine people as they slept in the latest tragedy to hit the country's vast railway network, officials said.

Authorities were trying to determine what caused the fire to break out before dawn, just hours after the train left Mumbai on a 48-hour journey to the Himalayan foothill town of Dehradun, Western Railways spokesman Sunil Singh said.

TV channels broadcast images of flames leaping out of the windows and lapping at the metal sides of the cars. Five of the victims had suffocated on smoke, while four were burned to death, Railway Minister Kotla Surya Prakash Reddy said.

The fire spread through three of the train's coaches before it was noticed by a guard at a railway post, who alerted railway authorities.

"We made the train stop immediately," railway official Shailendra Kumar said. Because there was no road access for firefighters, "passengers and train staff used fire extinguishers on the train to douse the fire, but it did not subside."

Firefighters eventually put out the blaze at a stop further along the track at the town of Gholvad in Maharashtra state.

The blackened and charred cars were unhooked from the rest of the train so it could continue its journey north.

The tragedy happened less than two weeks after another train fire killed 26 people in the southern state of Andhra Pradesh.

Accidents are common on India's railroad network, one of the world's largest, with 23 million passengers daily riding on about 11,000 passenger trains. Most collisions and fires are blamed on poor maintenance and human error.

Fires were involved in at least eight of the 100 or so accidents that killed 185 people in 2012, according to a 2013 safety review submitted to Parliament.

The railway ministry on Wednesday promised about $8,000 in compensation to the families of those killed on the Mumbai-Dehradun Express.