The Patna-bound Vasco Da Gama Express (12741) derailed at 4:18 am, soon after leaving platform number 2 of the Manikpur Railway Station in Chitrakoot district, about 250 km from Lucknow.
According to ADG (Law and Order), Anand Kumar, prima facie a fractured track led to the accident.
Railway Minister Piyush Goyal expressed grief over the accident and announced compensation for the families of those killed in the accident.
"Immediate rescue and relief operations started and an inquiry ordered into the derailment of Vasco De Gama-Patna Express at Manikpur, UP. My sincere condolences to the families of the deceased", Goyal tweeted.
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Chitrakoot SP Pratap Gopendra Singh said a father-son duo from Bettiah district of Bihar died on the spot while the third passenger died at a hospital.
"Of those injured, two were serious and admitted to district hospital, Chitrakoot. Seven with minor injuries are being treated at Manikpur," Singh said.
"The injured have been rushed to the hospital and officials have left for the spot. Relief operations are underway," Malviya said.
He said that soon after the accident, a medical train reached the spot and by 5:20 am, an accident relief train was dispatched for the spot.
Railway spokesperson Anil Saxena told PTI that the affected route has now been cleared for traffic.
There have been train derailments this year.
In August this year, 23 passengers were killed and 150 injured when the Utkal Kalinga Express derailed in Uttar Pradesh.