The victim, who was a passenger of the Brahmaputra Mail that was travelling to the national capital, was dragged to the mango orchard and gang-raped by the unidentified accused after she alighted from the train between Vikramshila and Kahalgaon stations, they said.
She was later murdered and her body hung from a tree late last night, sources said.
The police recovered the body today and sent it for post-mortem.
A railway ticket and cellphone number of her village pradhan written on a piece of paper was recovered from the victim's possession, the sources said.
Further investigation is on in the case.