Six men gang rape girl, 14, in Sydney

A teenage girl has been sexually assaulted by a gang of men in Sydney's west.

In an attack police believe was random, the 14-year-old girl was initially assaulted by one man in Doonside before his friends joined on Saturday night.

The first man approached the teenage girl about 11pm (AEDT) in Bill Colbourne Reserve on Hill End Road, police say.

Police have been told the man touched the girl inappropriately before sexually assaulting her.

"The man's five friends then also sexually assaulted her," police said in a statement on Sunday night.

The group of men then fled the scene, leaving the girl to walk to a nearby home where police were called.

The girl was taken to hospital for treatment.

Local detectives, with assistance from the State Crime Command's sex crimes squad, are investigating.

The men are all described as being of African appearance and aged in their late teens to early 20s.

Anyone with information can call crime stoppers on 1800 333 000.