The incident took place in a village in Madhuban area, where the girl was allegedly gangraped by Bablu, Pappu and Ramakant, they said.
The three also forcibly fed the girl with some poisonous substance to kill her after the rape.
The girl was rushed to a hospital after the villagers informed the family members. Her condition is stated to be serious.
An FIR has been registered against the three accused who are absconding.