The horrific attack on pedestrians at a busy intersection in Melbourne's CBD was not believed to be terror-related, Victoria Police have said.
Nineteen people were injured, including a four-year-old boy, after the driver of an SUV mowed down pedestrians on Flinders Street at Elizabeth Street on Thursday just before 5pm.
The child was taken to the Royal Children's Hospital with head injuries, while four other victims were critically injured and are fighting for their lives in city hospitals.
On Friday morning, the casualty count remained at 19, and four people were still in a critical condition. One of the injured is the driver suspected of carrying out the attack, who is under police guard and yet to be interviewed. Another is an off-duty police officer who stopped the rampage.
On Thursday afternoon, the driver, a 32-year-old Australian citizen of Afghan descent, was arrested at the scene by the off-duty police officer whose actions have been described as heroic.
Victoria Police Acting Chief Commissioner Shane Patton said the man was known to police in relation to minor traffic offences and a minor assault in 2010.
"At this time we don't have any evidence or intelligence to indicate a connection with terrorism," Mr Patton he said.
The driver also had a history of drug use and mental health issues, Mr Patton said. He is in St Vincent's hospital and is yet to be interviewed by police.
"Doctors will determine when he is fit for interview," Mr Patton said. "We will be hoping to interview him at the earliest possible stage.
A second 24-year-old man seen filming the crash was arrested shortly afterwards, but he was not believed to be involved in the incident. A 24-year-old man was charged overnight with drugs and weapons offences; police said there was no connection with the car attack.
Police said it was probable that he had no links to the incident and said the driver was alone in the car.
The Homicide Squad, Major Collision Investigation Unit and Counter Terrorism Command were investigating the incident, Mr Patton said.
The car was registered to a family member and police said it was not stolen.
The driver was about four cars back from traffic lights travelling west on Flinders Street before he drove up on the tram tracks and accelerated into pedestrians.
"We believe he's driven down the tram tracks and he crashed into a tram stop on the other side," Mr Patton said.
Victorian Premier Daniel Andrews described the incident as a "horrific act, an evil act, an act of cowardice perpetrated against innocent bystanders".
Seven people are in the Royal Melbourne Hospital, two are in a critical condition. Nine people were taken to The Alfred hospital, two are in a critical condition and another is in St Vincent's Hospital. Injured along with the four-year-old boy were; five men aged 24, 40, 43, 45 and 83 and six women, two aged 25, then four aged 30, 35, 47 and 58.
"What has occurred on Flinders Street was an act of evil and act of cowardice at a time of year when people should be out celebrating and doing their Christmas shopping," the Premier said.
"What we have seen is a horrific, evil, act and one that will be condemned by all Victorians, but at the worst of times we have also seen extraordinary courage from Victorians."
The area around the site of the attack reopened to trams and traffic about 2am.
Mr Andrews lauded the efforts of the off-duty police man who detained the driver and emergency services including police who arrived within "15 seconds" and paramedics who were there within minutes.
"He [the off-duty officer] deserves special praise for the way in which he instinctively came to the rescue of others avoiding so much further carnage," Mr Andrews said.
Mr Andrews commended the bystanders who "came to the aid of people who they had never met before".
Mr Patton said there was no ongoing threat to the public and told people to go about their business.
He said there would be hundreds of extra police on the streets of Melbourne's CBD and told Victorians not to be defined by the incident.
"We have to be strong, we have to continue on as a community... come in, go to the carols, go to the cricket," he said.
The attack occurred almost a year after the tragedy on Bourke Street, in which six people were killed and dozens more injured.
Asked what it meant to have two similar incidents happen in such quick succession, Mr Patton said: "It's life-changing for all emergency services that attend... and devastating for victims of this incident and those that were present will be changed forever."
- Anyone affected can contact the Victims Support Helpline on 1800 819 817.
- Anyone with information or videos can contact Crime Stoppers on 1800 333 000.