Police are urging women to walk in groups and stay in well-lit areas after a group of a men preyed on a teenager as she left a party in Sydney's northwest.
They are hunting a pack of five men who abducted and raped the 18-year-old just after she emerged from what police called a "sober" gathering at a house on Merindah Road, Baulkham Hills, about 1am (AEDT) on Sunday.
The men, in a green sedan, stopped the young woman and asked for directions to a local shopping centre.
She was dragged from the footpath into the car, restrained, driven to an unknown location, and raped by a number of the men.
Police believe the gang may have driven past the house party before the attack took place.
Detectives are checking to see if details of the gathering were posted on Facebook or made public in some other way.
Police described the party as a "fairly sober night".
They have warned women to take extra precautions but played down fears the same gang could strike again.
"There's certainly no suggestion we have a group of males preying on women," NSW police sex crimes squad commander Detective Superintendent John Kerlatec said on Monday.
"However, I would like to make it very clear, we do have an investigation into an offence where we don't know who committed these crimes."
He urged women to walk with friends, stay in well-lit areas, keep mobile telephones ready to hand and not to get close to anyone asking directions.
The victim was released from the car at Castle Hill and spent Sunday receiving medical treatment and the support of family, counsellors and the police.
She was traumatised and suffered a number of injuries.
"It's an horrendous incident for anyone to be subjected to," Det Sup Kerlatec added.
"A young lady walking along the street, regardless of the time of day, regardless of the place, should be able to walk safely.
"It was an extremely traumatic experience for her."
Witnesses, including people who were at the party, have already come forward to assist police.
One of the attackers is said to be Caucasian and aged about 25.
He was chubby, bearded and wore a red and white flannelette shirt.
Anyone with further information is asked to contact Crime Stoppers on 1800 333 000.