The victim filed a complaint today although the incident occurred on Sunday, Inspector General of Police Law and Order S N Singh told PTI.
"The accused driver and assistant of the bus have escaped. But our investigation is going on and shall book the culprits very soon," Singh said.
The former President of the All Adivasi Student Association of Assam (AASAA) Rafle Kujur said the girl had boarded the bus from Tezpur for Goreswar at about 2 pm.
The girl managed to escape from the bus early in the morning yesterday and rushed to an Adivasi village at Atrighat where the local AASAA unit came to the bus with police, but the driver and assistant escaped, he said.
AASAA acting President Prodip Nag said the girl, who hailed from Doimari village of Sonitpur district, was a domestic help in Guwahati, but she had fled due to some problems to stay with her relative in Goreswar.