Kolhapur, Jul 30: Kolhapur police have registered  a case of gangrape and blackmail against a physical instructor Devidas Raut and four Class XI students charging them with raping a 13-year-old girl, who was coming for karate training.

Two members of the gang have been arrested and the remaining three are absconding, police said.  

The gangrape incident took place two months ago in Lakshminarayan School, Singpur. The physical instructor, according to the victim's mother, waylaid the girl behind the girls' hostel with the help of four students, and gangraped her.  

The rapists recorded the heinous act on their cellphone, and for nearly two months they have been threatening the girl saying they would post the sex video on the internet, if she didn't agree to their demand for sexual intercourse.

On July 30, the physical instructor again called the victim to come to a secluded area behind the girls' hostel, and the police nabbed two of the accused.