The parents of the teenager had died and she was staying with her grandmother at Angiapeta village under Rayagada police station.
The three youths, who were later arrested, lifted her to a nearby jungle and raped her on the evening of January 2 when she was returning home from a shop where she worked, they said.
Unable to cope with the humiliation, she kept mum for a day and tried to set herself ablaze the next day when her grandmother was not at home, she informed from the bed of a hospital where she was admitted with 80 per cent burns.
The incident which came to light only yesterday sparking anger among the people, following which the administration shifted the victim to a private hospital at Vishakapatnam in Andhra Pradesh.
The state government would bear all the medical expenses, said Rayagada DC Sashi Bhushan Padhi.
SDPO (Rayagada) V N Rao said the three accused -- Muna Chhatriya, Malik Patria and Bharat Khosla -- all aged below 20 years, have been arrested.
"The accused are being interrogated. They will be produced in court after medical examination," he said.