The woman, whose wedding was fixed for April 22, was alone at her house in Samarpur Malda under Haldharpur police station when Guddu Yadav of the same village barged in and tried to force himself on her, they said.
When she opposed, he allegedly stuffed cloth in her mouth and set her afire before fleeing, Superintendent of Police (SP) S H Meena said.
Hearing her cries for help, the neighbours rushed her to a hospital in a serious condition.
