A maroon Holden Commodore brought an area of the city centre to a standstill today as the driver performed 'donut' manoeuvres outside the main train station while leaning out the window and shouting at onlookers.
Dimitrious "Jimmy" Gargasoulas, 26, has been named by local media as the man at the wheel.
As hundreds of people watched on, including police officers, the car then sped off at about 80km/hr towards the main Bourke Street Mall and mounted the pavement.
Police said he then drove 'deliberately' at pedestrians sending dozens of victims flying into the air - and hitting a pram which was later seen smashed in two with half lodged in the car bonnet.
Many of those injured were children as the area was packed with families enjoying the school holidays.
Several witnesses reported seeing a mother with a baby in a pram being hit at speed.
Police later confirmed a "young child", aged 10, was among the deceased while a man and woman, both aged in their 30s, were also killed.
A fourth death has also been confirmed by Victorian Police.
Four of the 20-odd injured people were still in hospital with life-threatening injuries and three of them were critical, local media said.
A two-year-old toddler was in intensive care in a serious condition while a nine-year-old is being treated for limb injuries and a 13-year-old was in stable condition.
Victoria Chief Commissioner Graham Ashton said the driver had no links to terrorism but was well-known to police and had an extensive history of family violence.
“He has come to our attention on many occasions in the past,” Mr Ashton said.
“That is mainly linked to drug issues and mental health problems.