Annoyed that the parents had fixed the marriage of the girl elsewhere, Mahto, along with two accomplicaes, met her at a place fixed by him last night and set her ablaze, Kumar said.
The critically burnt girl was rushed to government-run MGM hospital in Jamshedpur, where she died in the wee hours, he said.
Kumar said that one person was arrested, though the main accused was at large.
A motorcyle used by the three has been seized.