Five persons were killed and 36 injured when the Dehradun-bound 13009 Doon Express jumped the rails and skidded on the ground near Mehrwa station in Jaunpur district, about 200 km from Lucknow, on Thursday afternoon.
Of the 11 coaches that were stated to have derailed, six remained stable while five were mangled.
"The accident took place around 1.30 pm when the train was on its way from Howrah and heading towards Dehradun. According to some eye-witnesses, there was a sudden thud after which 11 coaches of the train jumped off the tracks. Luckily, no damage was caused to the six coaches, which remained on the ground; but five of the coaches went crashing on the sides, leaving five dead and 36 injured," Additional Director General of Police (Railways) Gurdarshan Singh told media persons in Lucknow.
He did not rule out the possibility of some passengers still remaining trapped in some of the mangled coaches lying on the tracks.
"The local administration and the Railway relief team were trying to cut open the mangled coaches to search of any dead body or an injured passenger was still trapped inside," he pointed out.
Singh said, "27 of the injured have been discharged after first-aid and arrangements were being made to transport them to their respective destinations."
On the possible cause for the accident, Railway Board member A P Mishra said that exact cause has to be ascertained.
It could have been "due to excessive heat causing track expansion or some miscreant activity," he said, adding that the railway track could be cleared by Friday morning.
"Assistant Loco Pilot has infomed railway officials that he had seen some obstruction in the track and he tried to apply brake. While 10 coaches passed, the last seven bogies derailed", Mishra said, adding that Railway Minister Mukul Roy is likely to reach the spot tonight.
Quoting the district magistrate and the superintendent of police of the area, about 70 kms from Varanasi, Mishra said the toll may rise but not substantially. The train was on its way from Howrah to Dehradun.
The train was running at 95 kms per hour when the driver suddenly applied the brake after seeing "some obstruction" on the track, he said.
The reason for the accident "will be known after the inquiry only. What the driver has stated is that he saw some obstruction on the track and the train was at 95 km speed. He applied the brake and the speed got reduced to 65 km. As a result, seven coaches were affected," he said.
"Initial reports have suggested that there was some deformity in the track. The track wasn't in proper shape. There was some kind of obstruction on the track...There can primarily be two reasons for this (accident).
"One that the temperature is too much these days. Due to heat, the tracks expand. There are chances of buckling. The second reason may be because of some miscreant activity," Mishra said.
Meanwhile, the Railway Minister, who was in Kolkata, has announced a compensation of Rs five lakh for the next of kin of those killed in the accident, Rs one lakh for those with grievous injuries and Rs 25,000 for those with simple injuries.
The minister also did not rule out possibility of sabotage, but said the inquiry will ascertain the real cause of accident, officials said.
Mishra said the railway authorities were making arrangements for the stranded passengers and they would be transported either by buses or special train. An accident relief train was also reaching the spot, he said.
Asked how long will it take to restore the railway line, he said, "It will take 14 to 15 hours."
On May 22 in Penukonda in Andhra Pradesh, 25 passengers were killed, 16 of them charred, and 43 injured when the Bengaluru-bound Hampi Express rammed into a stationary goods train after its driver apparently overshot the signal near the station.