New Delhi, India (CNN) Seven people are under arrest in India after a 15-year-old alleged she was repeatedly raped by 19 people -- three adults and 16 minors -- over six months, Anuj Kumar, sub-inspector of the Ekma police station in eastern Bihar state told CNN.

The girl allegedly was raped by a group of three to four boys in an initial incident, Kumar said. The others learned of the rape and threatened to expose it, then also raped her, he said.

The victim filed a complaint on July 6, Kumar said. The police have arrested the principal, two teachers and four minor boys, he said.

"We are investigating," said Vijay Kumar Verma, deputy inspector general in Saran, a district of Bihar state. "We will take warrants out from the court and conduct raids" to catch the rest of the boys.

The suspects deny involvement in the incidents, Kumar told CNN.

Read More