The incident took place on Tuesday when the woman, a mother of three, was on her way to a bank where the three accused kidnapped her at gunpoint, they said.
They then took her to a nearby forest and gangraped her, police said.
The victim was also robbed off her valuables including money, jewelery and mobile phone, and assaulted until she fell unconscious, police said, adding, the accused fled the spot.
Later, the locals found the woman in an unconscious state and took her to a hospital, they said. Based on her complaint, the police have lodged a case of gangrape and robbery against the accused and efforts are on to nab them.