Police also said that seven other persons have been detained for questioning in this regard.
The minor girl, who hailed from Cheralia village, had been raped and later killed by unidentified persons.
One Gakul Orang (26) was arrested for being allegedly involved in the crime.
Among the persons detained for questioning are Dipen Orang (22), Sam Orang (27) and August Orang (28), while the identity of the other four have not been disclosed.
The minor's body was recovered from a paddy field near Cheralia village yesterday by some locals who later informed the police.
Various organisations, including the All Adivasi Students Association of Assam (AASAA,) have condemned the incident and demanded immediate arrest and punishment of the culprits.