The 16-year-old girl, who cannot be named for legal reasons, was married off by her family in the western state of Rajasthan, where child marriage is particularly prevalent.
In May, relatives forced her to leave school and go to a nearby village to live with her husband and his family.
But her classmates tracked her down to her new home, some walking barefoot for miles to reach her.
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"They somehow tracked down the house and met the girl who told them that she wanted to continue studies and was not willing to stay with her husband and in-laws," said Gopal Singh, a teacher with the non-profit Sakhi Bal Niketan which helped the friends unite.
At first police refused to listen to them, but they found a number for the topmost administrative official of the district scribbled on the walls of the police station and enlisted his help.
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"I made some phone calls to the officials and authorities and she was rescued and rejoined the school after that," district collector Siddarth Mahajan told AFP.
The legal marriage age for girls in India is 18, but millions of children are married when they are much younger, particularly in poor rural areas.
The custom is particularly strong in Rajasthan where politically powerful village councils have an iron grip over social and moral life.
The Hindustan Times daily Thursday said the teenager returned to the school to a hero's welcome and has since asked the local family court to annul her marriage.
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