At least 23 people were killed and 123 injured in a train crash in northern India, the fourth major accident over the past year on the world's fourth biggest rail network, which is grappling with chronic under-investment and overcrowding.
Emergency crews searched mangled carriages for more victims on Sunday, a day after coaches were left in a mangled heap after an express train derailed at 100 kilometres per hour, crashing into nearby houses and a college.
The cause of the derailment — in the state of Uttar Pradesh, about 130 kilometres north of the capital New Delhi - was not known, said Northern Railways spokesman Neeraj Sharma, but the driver of the train would be one of the first people to be questioned. He said the death toll could rise.
Thirteen coaches of the train came off the tracks as it was heading to the Hindu holy city of Haridwar, police said.
"We are checking the coaches thoroughly for any survivors or bodies. We will clear the tracks today," Anant Dev, Muzaffarnagar district police chief, said.
Rescuers used gas-powered saws to prise apart the tangled metal and search the wreckage with sniffer dogs.
A large crowd descended on the accident site to help free passengers from the damaged carriages, many of which were upended and torn open.
Some of the injured were seriously hurt but many had been released from hospital after receiving treatment, Mr Dev said.
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The Utkal-Kalinga express left Puri, a Temple City in India's coastal east, on Thursday evening and was scheduled to arrive in the northern Hindu holy city of Haridwar on Sunday.
The government has ordered an inquiry into the accident amid speculation unscheduled maintenance work was under way at the time.
A senior official in the Uttar Pradesh government, Arvind Kumar, told the Hindustan Times the train driver had slammed on the brakes after spotting maintenance work on the tracks that had not been properly signalled.
Mohammad Jamshed, a senior official with the government's railway board, said some repair equipment was found near the accident site - indicating work was being carried out.
But he cautioned that the evidence was inconclusive and a thorough probe would unveil the exact cause of the crash.
"The investigation will deal with all the aspects, be it technical, human error or sabotage," Mr Jamshed said.
Railways minister Suresh Prabhu vowed in a Twitter message to "fix responsibility" for the crash.
Criminal investigators were also probing whether sabotage was involved.
India's railway network remains the main form of travel in the vast country.
Train crashes are common in India after decades of poor investment and rising demand, which usually mean packed trains are running on creaking infrastructure.
Experts blame under-investment and poor safety standards for the frequency of rail accidents.
This latest derailment is the fourth major crash this year, and follows another accident in Uttar Pradesh last November that left 146 dead.
A 2012 government report described the loss of 15,000 passengers to rail accidents every year in India as a "massacre".
Prime minister Narendra Modi has pledged $137 billion (Dh503bn) over five years to modernise the crumbling railways and his government has signed numerous upgrading deals with private companies.
Japan has agreed to provide $12bn in soft loans to build India's first bullet train, with its prime minister Shinzo Abe and Mr Modi tipped to break ground on the project in September.
In addition, the government launched a $15bn safety overhaul in February after the surge in accidents blamed on defective tracks.
But in June, Reuters reported that the overhaul was facing delays as the state steel company could not meet demand for new rails.