The truck has gone through the McDonald’s car park colliding with at least three cars before pinning a fourth car up against the fence of the North Gate unit complex.

Seven ambulance crews responded to the incident with paramedics treating a number of patients including a 35-year-old male in a serious condition, a 17-year-old female and a woman in her 50s.

A NSW Ambulance spokesman said the truck driver, in his 20s, was being treated for lower back injuries.

A witness who was parked close by said he saw a truck “fly through the roundabout and up over a couple of cars”.

The man said he ran to the back of Maccas to help the driver out of the truck and then around to an injured woman in her car.

He said the woman appeared to be in shock and had cuts and bruises. It’s understood the woman has been taken to Wollongong Hospital for treatment.

A silver Honda CRV has come to rest on a burst water main. A second water main has ruptured at the back of the car park where the truck is.

The truck is a Hino table top and appears to be carrying a load of building material when it came unstuck.

It has come to rest nose-to-nose with a white SUV which has been badly crumpled and pushed backwards through the steel pole fence of the North Gate complex.

Some anxious parents of McDonald’s staffers have begun arriving.

The restaurant has been closed and is expected to remain closed for most of the day.

It's not the first time the McDonald's car park at Fairy Meadow has been the scene of a serious accident.

In December 2009 a runaway truck overloaded with steel building material sped down Mt Ousley Road, across the Princes Highway roundabout and into the car park

Fifteen people were rushed to hospital after the crash, including four children who were among a group from a day care centre heading to a Wiggles concert at WIN Entertainment Centre.