The truck went through the McDonald’s car park colliding with at least three cars before pinning a fourth car up against the fence of the Northgate unit complex about 10.45am.

Seven ambulance crews responded to the incident with paramedics treating a number of patients including an 18-year-old girl and a woman in her 60s.

NSW Ambulance Wollongong chief inspector Terry Morrow said the teenage victim, who is believed to have been driving the car that was first hit by the truck, reported tenderness around her neck and spinal area and was treated for spinal precautions.

The woman whose white SUV became pinned between the truck and the fence is the most seriously injured. She was trapped for 15-20 minutes and suffered head and chest injuries, Inspector Morrow said.

She suffered a concussion and two or three fractured ribs and pelvic injuries and will be further assessed at Wollongong Hospital.

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

Inspector Morrow said the truck driver appeared to be “confused and disorientated” about what had actually happened.

“He was very emotionally distressed.”

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 the McDonald’s restaurant to help the driver out of the truck and then around to an injured woman in her car.

The incident ruptured two water mains in the area.

Read more: Police probe explosion at North Wollongong unit block

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

It came to rest nose-to-nose with a white SUV which was badly crumpled and pushed backwards through the steel pole fence of the Northgate complex.

The McDonald’s restaurant is expected to remain closed for the rest 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.

NB. NSW Ambulance earlier released a statement saying four people were injured at Fairy Meadow Monday morning. It is understood there are only three people with injuries.