The last thing Uttam Kumar remembers is a huge bang as his carriage was violently crushed. When he came to, he was trapped upside down in the wreckage of an Indian train that derailed on Sunday, killing more than 140 people.

Fighting back tears, the 26-year-old business student recalled how he waited over three hours to be cut out of the mangled train carriage, which was crushed under another by the violence of the crash.

When rescuers finally put him in an ambulance, there were only dead bodies for company.

"It was like being in a nightmare. It was happening, but I couldn't believe it was happening," he told AFP from his hospital bed in the northern city of Kanpur near the accident site.

"They cut the part of the carriage where I was stuck and pulled me out. Then I remember being moved to the ambulance, which was parked next to the site. I was the only one alive among all the dead bodies."

An estimated 2,000 people were on board the intercity express train when it came off the tracks around 3 am on Sunday, violently jolting passengers out of their sleep.

Relatives have since flocked to the crash site and to nearby hospitals desperate for news of loved ones on the train, which was carrying at least one wedding party with the marriage season in India in full swing.

So far 142 bodies have been pulled from the mangled wreckage, a painstaking process involving metal cutters, heavy lifting equipment and sniffer dogs.

Rescue workers say many of the bodies are so badly damaged they are unrecognisable, and expect the toll to rise further as the worst affected carriages are cleared.

- 'Where is she?' -

Vivek Parikh, whose two sisters were on the train, left for Kanpur from his home town around 350 kilometres (215 miles) away as soon as he heard of the disaster.

One sister was confirmed dead, but he spent the night desperately searching Kanpur's hospitals for the other.

"No hospital or location has any clue or detail about Roshni. Where is she?" he said as he rushed from one hospital official to another pleading for information.

Kumar's family managed to track him down quickly thanks to the help of local residents, who heard his screams for help from the wreckage and took down his home telephone number so they could contact his relatives.

"The people heard my screams but no one could do anything as the carriage was crushed under another carriage," he said. "(So) I shouted my home telephone number loud for anyone who could hear."

Kumar suffered head and back injuries, but his biggest concern is finding his 75-year-old grandfather, who was sitting next to him on the train.

The pair had been on a pilgrimage to Ujjain -- famed for its temples -- and were on their way home to the eastern city of Patna, the train's final destination.

"I don't know what happened to him. He was on a seat beside me," he said.

"Now he is not in any of the two lists -- of victims and survivors. No one has a clue about where he is."

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