The boys, who have been caught, claim to be minors between 15 and 16 years of age.
The girl was playing near her house, when they drugged her and took her to an isolated spot where they gangraped her through the night.
Based on the boys' claim, a bone marrow test will be done to determine their age. Meanwhile, the girl, who was found by her parents the next day, is at a women's home.
She was taken to a hospital where medical reports confirmed rape.
The accused, who were nabbed by the police were held at an observation centre in Guwahati
Their age plays a crucial role in the case as juveniles in rape cases have drawn a lot of flak in the recent times, sparking off debate about their punishment.