The woman said her friend had taken her to Outer Ring Road in Bangalore in a car and raped her. The man, whom she befriended two months ago, left her in a secluded area.
The woman added a group of bike-borne men arrived soon after, took her forcibly to a building and gang-raped her.
According to the woman, when she tried to run away, she was thrown out of a window on the second floor. The woman suffered serious injuries on her legs and back.
Bangalore additional commissioner Kamal Pant said the woman was taken to a hospital by local residents who found her lying near the building.
"The police have started an investigation into the matter," Pant said.