A young teen has been ambushed by a group of girls while waiting for the bus about 7pm on Friday.

The 14-year-old girl was allegedly forced at knifepoint down Longstaff Wy, to where a dead end meets a reserve backing onto the Hume Hwy at Claymore, in Sydney’s suburban southwest.

Three girls then allegedly punched and kicked the young victim before forcing her to strip naked, NSW Police.

Know the news with the 7NEWS app: Download today

She was then allegedly whipped with a phone cord — all the while, the incident was being recorded, NSW Police

The three teen offenders then allegedly fled with the the victim’s top, pants, shoes and mobile phone.

PolAir were involved in the search, and three girls were arrested nearby.

The three 13-year-old girls are all known to the victim, police said.

They were all charged aggravated robbery with offensive weapon, and aggravated – cause etc 14 years or over to make child abuse material.

One was also charged with possess child abuse material.

They have been refused bail to face a children’s court on Saturday.