A LITTLE boy killed by an out-of-control car had been holding his dad’s hand when the 4WD began ploughing into cars and pedestrians, in a horrific accident in Melbourne’s southeast.

Nurses from a nearby medical clinic desperately tried to save the four-year-old as he lay motionless in the Berwick carpark, while his parents watched on.

media_camera Flowers and toys are left at the scene in a car park where the 4-year-old was killed. Picture: Hamish Blair

Paramedics took the boy to hospital — just 300m from the scene — but he could not be revived.

Investigations were on Friday night under way to determine why the driver of the LandCruiser lost control with such devastating consequences.

Major Collisions Unit Detective Sergeant Mark Amos shook his head as he imagined how the Narre Warren South parents were coping with their son’s death.

“It is just the most horrible, horrible thing you can imagine,” Sgt Amos said.

“We have to find answers.”

media_camera The Toyota 4WD that smashed into a carpark and killed a child. Picture: Steve Tanner

media_camera The out-of-control 4WD also damaged a number of parked cars before it ended up on its side. Picture: Steve Tanner

media_camera A aerial view of the crash aftermath in Berwick. Picture: Channel 7 News

Police were probing whether the motorist, a 56-year-old from Pakenham, had fainted or become dizzy behind the wheel.

The man told first-aiders he had been receiving dialysis treatment at nearby Casey Hospital.

Patients new to undergoing dialysis — a treatment for kidney failure, which usually takes up to five hours — are usually told not to drive afterwards.

Shocking scenes unfolded on Kangan Drive about midday when the man left the hospital and swerved over a median strip. His car drove up an embankment into a carpark where patients from a busy medical centre and their families were standing.

media_camera How the tragic crash occurred.

Cameron and Sarah Smith were travelling behind the LandCruiser when they saw it become “airborne” before it smashed into 10 parked cars outside the Epworth Specialist Centre.

“We have two sons of our own, that age,” an emotional Mrs Smith said.

“I remember the dad saying ‘it’s my fault’ — it’s not his fault. Those poor parents.”

Mr Smith ran to the smashed-up LandCruiser to check on the driver, who was conscious but trapped inside the car.

“He stated that he had dialysis, he’s just had blood taken out,” he said.

media_camera Cameron and Sarah Smith witnessed the incident and were overcome with emotion at news of the child’s death. Picture: Steve Tanner

media_camera Sarah Smith breaks down at the scene of the tragic crash. Picture: Steve Tanner media_camera Cameron Smith rendered assistance at the scene.

media_camera Kangan Drive has been closed between Clyde Rd and Casey Hospital after the horror crash. Picture: Steve Tanner

media_camera The 4WD on its side. Picture: Channel 9

A woman in her 60s was also clipped by the car. She was on Friday night recovering in hospital.

Sgt Amos praised the efforts of bystanders who rushed to help.

“They couldn’t have done any more than what they did,” he said.

Police were at Casey Hospital on Friday night to determine the driver’s movements, and whether he had received medical treatment, before he drove off in his LandCruiser.

The man was yet to be formally questioned.

andrea.hamblin@news.com.au