"It is believed that just before midday a light green 100 series Toyota LandCruiser was driving on Kangan Drive.
"The four wheel drive has driven through a car park and struck and killed a 4-year-old boy."
Paramedics and firefighters were also on the scene.
Visuals taken from a Seven News helicopter from above the incident show a 4WD flipped on its side and numerous cars smashed around it.
"Paramedics were called to a road crash just before midday in Kangan Drive at Berwick," a statement from Ambulance Victoria read.
"On arrival, they found three people with injuries. One of them was a young child who was in a critical condition.
"A man, believed to be in his 50s, was taken to Dandenong Hospital in a stable condition.
"A woman, believed to be in her 60s, was taken to Casey Hospital with minor injuries."