The girl suffered nearly 75 per cent burns and is being treated at a government hospital in Bikaner, SP Rahul Katakey said.
According to the victim's statement, Vicky, Sonu and Vijay raped her on the roof of her house on Thursday night and set her ablaze yesterday morning, he said.
The victim's parents were not at home when the incident took place.
A case has been registered against the accused under relevant sections of Protection of Children from Sexual Offences (POCSO) Act.