Man's leg torn off while fixing buggy

A man was fixing a dune buggy at a property in Sydney's outer west when he was hit by a car, resulting in his leg being torn off below the knee.

The 23-year-old man was fixing the dune buggy at a farm road at Greendale, when a woman driving a Holden Monaro apparently hit him about 7pm yesterday.

It is believed a third vehicle was also involved in the incident.

The man was found in an unconscious state - with his right leg torn off below his knee - by ambulance paramedics who treated him, NRMA CareFlight spokesman Ian Badham said.

After stabilising him, the man was flown to Liverpool Hospital, where he was in a serious but stable condition.

Three women including the driver, believed to be in their early 30s, were travelling in the Holden Monaro.

They sustained minor injuries and were also treated by ambulance paramedics.

Police are investigating the incident.

- AAP