Several witnesses have come forward to provide police with information on a shocking gang rape attack on a student in north-west Sydney.

An 18-year-old woman was abducted by a carload of five men and assaulted after leaving a house party at 1am on Sunday, police said.

Merindah Street, Baulkham Hills, where a woman was abducted and sexually assaulted. Credit:Rachel Olding

The woman, a year 12 student at a local high school, has told police she was driven to an unknown location where she was repeatedly raped and physically assaulted before she was dumped on a Castle Hill street. She made her way home and then phoned a relative for help.

The victim was so traumatised she was only able to recount scant details to police, describing the car as a green sedan and the man in the front passenger seat as around 25 years old, chubby, with a beard and wearing a red and white flannelette shirt at the time.