The accused have been identified as Nageen Gupta, his brother Ashu Gupta and friend Nicky.
The victim is a resident of Bhawanpur area here while Nageen is a resident of Sashtri Nagar.
According to the FIR lodged by the victim, Nageen had developed a relationship with the victim by hiding the fact that he was already married. He promised to marry the girl and exploited her physically, police said.
However, the girl got to know about Nageen's marital status on October 11 and she confronted him.
On this, he called her to a restaurant for a conversation on October 18, they said.
At the restaurant, the girl met Nageen accompanied by his brother Ashu and friend Nicky. The youths then took the girlto a house in Pallavpuram area where they allegedly intoxicated and raped her, they said.
On regaining consciousness, the victim found herself in a ground, from where she went home. She later called up Nageen, who told her that she had been gangraped and a video of the act has been made. He told her that if she talked about the incident with anyone, he would upload the video on the internet, police said.
A case has been registered against the three at the Bhawanpur women police station and efforts are being made to arrest the accused, police said.