"We arrested the four accused today (Sunday) morning under section 376G of the Indian Penal Code after the 20-year-old woman lodged a complaint with the local police station on Saturday," Mandya Superintendant of Police Bhushan Gulab Borase told IANS.
Mandya is about 100 km from Bengaluru.
The accused, aged 21-26, were identified as Kirti Gowda, Kiran Gowda, Mohan Kumar and Manju.
"The incident happened on a hillock (Beedibetta) near Pandavapura town where the woman was taken on a bike by Kirti whom she claimed to be an acquaintance, while the other three accused are his friends, who rode on bikes to the hilltop," Borase said quoting from the woman's police complaint.
Manju was present at the crime spot but did not rape the woman, the official said.
"The medical report of the woman is awaited from the state-run Mandya hospital where she was taken for check-up," Borase added.
The woman is a student of Maharani College in Mysuru, about 150 km from here.
Police also seized three motorbikes which the accused used in riding to the hilltop.
This was the second such incident reported in the state a week after a 22-year-old woman call centre employee was allegedly gang-raped in a moving van by the driver and a cleaner on the night of October 3 on the pretext of dropping her home from a bus stop while returning from work.
The accused were arrested on October 6 after the woman complained to police.