Four men who are said to have got off the Samjhauta Express — two as the train pulled out of the station, two as it slowed down before Diwana last night — could hold the key as investigators set out to put the pieces together.

Officials said they will question Rana Shaukat Ali, one of the injured admitted to Safdarjung Hospital in Delhi (see his story below), who told authorities he saw two men in his coach get into an altercation with an RPF constable near the Samalkha railway station. Kashmir Singh, the constable, died in the explosion later.

Sources quoted Ali as having told officials he overheard two “suspicious-looking” men as telling the constable that they wanted to go to Ahmedabad. “When they were told the train does not go to Ahmedabad, they said they would get off when it slows down,” sources said, quoting Ali.

Ali apparently saw the two men — they had mufflers on — jump off the train as it slowed before Diwana railway station.

Within minutes, the bombs went off, sources quoted Ali as having said.

Senior RPF officials said there were also inputs that two persons disembarked as soon as the train moved out of Old Delhi. “Many people noticed the two getting off but assumed they had come to see off someone,” a senior RPF official said.

The security establishment is also looking at reports that 4-5 persons conducted a “dry run” at the Old Delhi railway station in January before using a cocktail of ammonium nitrate, kerosene and sulphur to set off explosions on the train last night.

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