The incident came to light after the 16-year-old victim managed to escape from the clutches of the accused.
Prakasam's Superintendent of Police Siddharth Kaushal told a news conference that four accused were apprehended on Saturday and the remaining two nabbed on Sunday.
The girl, hailing from Guntur district, had come to Ongole town on June 16, looking for a youth with him she had developed friendship in Guntur.
When she was enquiring about him at the bus station, a youth working at a mobile phone store offered to help her. He took her to a room in the town where he locked and raped her.
Later, the accused brought five more youth who all raped her. The accused continued committing the crime for six days.
On Saturday, the victim managed to escape and reached the bus station. A policeman, who found her crying, took her to police station, where she revealed the shocking story.
The police formed special teams, which identified the accused and took them into custody.
Four of the accused are engineering students.
Police booked the accused under POCSO Act and various sections of the Indian Penal Code.
The victim was shifted to RIMS Hospital in Ongole. State minister B. Srinivas Reddy visited the hospital and assured that the government would ensure early and stringent punishment to the accused.
( With inputs from IANS )