Map of India showing the area in Andhra Pradesh state where a fire broke out on a passenger train early Monday.
At least 32 people were killed Monday when a fire ripped through a coach on an express train as it carried sleeping passengers to the southern Indian city of Chennai, officials said.
The accident, on a long-distance service from New Delhi, occurred in the early hours of the morning near the town of Nellore in Andhra Pradesh state with an electrical short-circuit seen as the most likely cause.
"Thirty-two (bodies) have been pulled out from the coach," Madhusudan Sarma, a senior administrative officer in Nellore district, told AFP, adding that there were still more corpses inside.
Another 26 people have been admitted to hospital, he added.
One carriage was completely gutted, and rescuers were struggling with the fierce temperatures inside the mostly metal structure. Cutting torches were being used to open wider access points for the emergency services.
Images showed dozens of rescuers, survivors and crowds of onlookers milling around as the blackened and twisted bodies of victims were lifted out of the wrecked carriage and laid in rows alongside the railway line.
Family members of the victims wailed and screamed, while other dazed survivors sat around quietly with their belongings.
"I woke up when people were rushing into our compartment, I was in S-10 which was attached to the S-11 coach that caught fire," passenger Shantanu, who gave only one name, told the NDTV news channel.
"There was smoke all around. We tried to open the emergency window, people jumped out of it."
Nellore chief district official B. Sreedhar said preliminary investigations suggested a short circuit near a toilet had triggered the blaze.
"We expect the death toll in the affected coach to be around 30 to 35 people," Sreedhar told NDTV. "The fire spread fast and blocked the door at one end of the coach, so there was only one exit available."
The non-stop train was travelling at 110 kilometers per hour (70 miles per hour) when it passed through Nellore station, where staff noticed the fire and informed the railway authorities.
India's accident-prone rail network is still the main form of long-distance travel in the huge country, despite fierce competition from private airlines.
While new shiny airport infrastructure is springing up across the country, the Indian railways -- a much romanticised legacy of British colonial rule -- often appear stuck in a time-warp.
There were two fatal accidents this May alone, including a collision that killed 25 people near the southern city of Bangalore. Four passengers also died after a train derailed in the northern state of Uttar Pradesh.
Prime Minister Manmohan Singh sent his condolences to the victims and has asked the national railways ministry to coordinate the relief effort, his office said.
In March, the then railway minister Dinesh Trivedi unveiled a draft budget for 2012-13 that included a major safety upgrade to be financed by across-the-board fare hikes.
But he was forced to withdraw it and resign after a rebellion from his own populist party, the Trinamool Congress, which objected to increasing ticket prices for the poorest travellers.
The National Crime Records Bureau, which gathers the causes of fatalities across India, says 25,705 people in total died on the railways in 2009.
The data is not broken down, but a vast majority of these deaths are people falling from the open doors of carriages or being hit on the tracks, which are mostly unsecured.
India's worst rail accident was in 1981 when a train plunged into a river in the eastern state of Bihar, killing an estimated 800 people.