The incident took place in Naini, around 25 kms from the city, last night when the constables - Arvind Dwivedi, Rajiv Kumar and Sant Kumar - were hit by Rajendra Nagar-Kurla Express while chasing Saleem whom they were bringing back to the Naini Central Prison after producing him before a court in Mirzapur district, a police spokesman said today.
While Dwivedi died on the spot, the other two constables were admitted to a hospital in a serious condition, he said, adding Saleem had been in jail in connection with a number of cases, including murder.
After being produced before the Mirzapur court in connection with a theft case, he was being brought to the Naini Central Prison by Janata Express.
The criminal pretended that he was sick and requested the constables to allow him to use the toilet.
However, he pulled the chain on way to the toilet and jumped out of the train, the spokesman said, adding the policemen were caught unawares and they tried to chase him but ended up meeting with the accident which proved fatal for one of them.
A search was on for Saleem, who has in the past made at least two attempts to escape from custody by assaulting the policemen accompanying him, the spokesman said.
Besides, an investigation was on into any alleged laxity on part of the constables who appeared to have consumed alcohol and failed to handcuff the criminal, the spokesman added.