• 29 people injured - 6 critically including a three-month-old baby who is in surgery;
• Driver has been arrested after being shot in the arm by officers - he has a history of mental health and drug issues and is well-known to police;
• Man linked to stabbing in the early hours of this morning in Melbourne suburb of Windsor - and the kidnapping of a woman
The driver who deliberately mowed down pedestrians in a busy Melbourne shopping mall - killing four, including a 10-year-old child, and injuring 29 others - was well-known to police and has a history of mental health and drug problems.
The man is 26-year-old James 'Jimmy' Gargasoulas who also goes by the name Dimitrious, The Age reports.
He was charged over a family violence incident less than a week ago.
A relative said the 26-year-old had a history of drug problems and had been in out of jail for car theft and drug offences, The Age reported.
"Jimmy has always been a bad person," the woman told The Age.
"I knew it was him. I saw it on TV ... the picture of him sticking his head out when he was doing burnouts.
"I balled out crying when they announced that baby died. I'm shaking, I just can't believe this."
The police chase through Melbourne's Bourke St mall ended in gunfire on Friday, with police shooting the driver in the arm in front of shocked lunchtime shoppers. He is in hospital under police guard with non life-threatening injuries.
As well as the 10-year-old victim, police said a man and woman, both in their 30s, were killed.
Victoria Police confirmed at 11:30pm (NZT) a fourth person had died as a result of the incident. They didn't release any details about the person.
Several other children were among the casualties including a critically injured baby.
The car - driven by a Greek man, 26, who had been involved in a stabbing with his brother earlier in the day and was well-known to police - ploughed through the crowd in Bourke St mall about 1.30pm (3.30pm NZT) on Friday.
He was pulled from his car by police and seen shirtless and lying only in his underwear, surrounded by officers.
Witnesses say a pram - and a child - were hit by the car and dragged at least 100 metres.
A three-month-old baby is in surgery with critical injuries.
"Where is my baby, where is my baby," a frantic mother was heard screaming.
Victorian premier Daniel Andrews said: "Our hearts are breaking this afternoon that a number of people have died. Others remain in a critical condition - very, very seriously ill, gravely ill - in hospitals around our city.
"But we are stronger than this. Through our response, through the work of our emergency services [and] the instinctive way in which Victorians have reached out to support each other, we can be confident that we are stronger than this evil criminal act."
A woman, who was too traumatised to speak on camera, told Sky News that she estimated the driver was travelling at 80km/h. She said she saw the car hit a pram and "saw a baby fly out."
Another witness, Sian Bayliss, said the driver "was just driving in a really determined fashion, just in a straight line".
"There was no hesitancy as he got to the crowds, he didn't swerve, he just drove right through them."
He said the footpath was full of people.
"I've got years of first-aid training so the moment I realised what had happened - as soon as the police had driven past and it was safe - I ran across to the other side to see who needed treatment.
"I got to [a] young man who has passed away - I don't think there was anything we could have done for him."
One young boy, aged about nine, had a bad abrasion to his head.
"There was just constant, high-pitched, panicked screaming, the terror in his eyes -he just looked straight at me while I was talking to his father and just... screaming. Out of control."
Others had terrible injuries.
"You know, there was one lady who looked like she had had a fairly serious spinal injury. They were just holding her very, very still, and it felt like a long time. . But the response time was great, but every minute seems like an hour, so she was lying there waiting for what felt like a very long time."
St Vincent's Hospital said it was caring for three women in their 30s, two men in their 40s and a 31-year-old man. All are stable with severe injuries.
As well as the critically ill baby, the Royal Children's Hospital is treating a two-year-old in a serious condition, a nine-year-old and a 23-year-old with limb injuries, and it is assessing a 12-year-old.
The Alfred is treating seven patients - two are critical but stable, two are seriously hurt and three are stable.
The carnage unfolded shortly after the driver began doing 360 degree doughnuts in the middle of the main Bourke Street intersection near Flinders St station, holding up traffic and causing pedestrians to run for their lives.
The driver then sped down King St, chased by police.
A CBD worker wrote on Twitter: "Was in Bourke St Mall when the driver who caused the police operation in #Melbourne went past. Shirtless, cigarette hanging out of his mouth"
A witness, Chris, told Sky News: "There were two people [taken in an ambulance]. Another rushed into a police car. I understand there are more people down the road (near King St). Just a hell of a lot of blood.
"I feel pretty moved and quite sick. It's a horrible thing to have had happened. I was standing by the pram for a while and when police got here they screamed for everybody to get back and move."
Police said the driver was well-known to them and had been charged last weekend into a family violence incident. He had a history of mental health and drug issues.
Police believe the man had been on a criminal rampage since the early hours of Friday.
He is accused of stabbing his brother in the southeast Melbourne suburb of Windsor about 2am, and at around 11.45am police tried to pull him over on the Bolte Bridge armed with guns and tasers but aborted their pursuit because his driving was too dangerous.
At one point, a woman had been taken hostage by the driver but she escaped from the car before the man drove to the central city and started performing the doughnuts. Police said she was not connected to the man.
Police Chief Commissioner Graham Ashton went through the afternoon's events and what police did minutes before the driver was apprehended.
"Police have intercepted the vehicle. As I understand it, rammed the vehicle. The offender has been taken into custody. During that process, the offender has been shot by police - he's been injured and we believe he's been hit in the arm.
"Those injuries are being treated at the moment in the hospital. That offender is at hospital under police guard, obviously, being treated for those injuries that we regard as non-life threatening at this stage.''
Three of the deceased victims were hit at different locations, Ashton said, so it was not believed that they were related or known to each other.
The driver was arrested at the Elizabeth St end of the mall, and was seen lying on the ground dressed only in red underwear and white shoes with police standing over him.
The mangled wreckage of half a pram was stuck on the bonnet of the car, while what appeared to be the other half was about 100 metres further up the mall at a pedestrian crossing on William St.
Two American tourists, Michelle and Daryl, said they saw the pram lying on the side of the street. People were running everywhere as were police with their "guns drawn".
"I heard at least five shots. Then we started trying to find cover in one of the buildings," Daryl said.
Michelle added: "(I was) stunned when I saw them drawing their weapons. People started screaming. We ran the opposite direction of police."
Anna Hellberg of Finland was just up the street from where pedestrians were hit.
"There was all this noise and then we saw a dark red car coming towards us. It was really mashed up at the front as though it had hit a a lot of things.
"We were right next to it when police were shooting at it. We could see the guy driving. He had a cigarette hanging out of his mouth. He looked stressed."
Hellberg saw paramedics working on a little girl who she believed was the baby who went flying from a pram.
"I couldn't really see her. There was a lot of police around her and paramedics were performing CPR."
She also saw a man lying on the footpath with blood coming from his head.
A Kiwi living in Melbourne, Erik Liang, described seeing the red car careening down the road onto Bourke St with police cars following.
"Me and my mate were sitting lunch when we finished up, this was about 1:30, we heard some sirens then this red car went through the streets and onto the footpath.
"We thought, 'what the hell is happening?'.
After the car went around the corner Liang said they started hearing some gunshots and saw people lying on the ground - one was being given CPR.
"It's horrifying," Liang said. "I go down that street every single day.
"It's absolutely shocking seeing something like that happen in your own backyard."
He said after the car went past, police worked to clear people from the scene.
"Everyone was just crying; it was a really sombre tone."
NZME's Mix radio host Mel Homer was also near the scene.
"An eye witness told me they saw a red car come up the road and onto the footpath. They thought it had hit at least 30 pedestrians.
"I can see several people lying on the footpath... at last six or seven [people]."
Homer told Newstalk ZB there was a lot of police at the scene, who were expanding the size of the cordon.
"Emergency services are just arriving."
Homer was having lunch when she heard helicopters and sirens and went outside to see what was happening.
A witness told Sky News Australia there was a "hell of a lot of blood" when he saw injured people being taken away by emergency services.
Melbourne is currently the focus of the sporting world, with the globe's best tennis players in town - along with thousands of fans - for the Australian Open.
STATEMENT FROM VICTORIAN PREMIER DANIEL ANDREWS
Daniel Andrews praised people who were first on scene to help those who had been injured.
He thanked emergency workers, but also ordinary people who took it upon themselves to help people they did not know but who needed them at that moment.
"Our emergency services have this afternoon done us proud. They've done a great job in the most difficult of circumstances.
"They have supported the most vulnerable, they have apprehended the person involved in this terrible criminal act - and we can all be confident that he is now in custody. And given that there are no links to terrorist organisations, no links to any other criminal activity, he is no longer a threat to the safety of law-abiding, decent, hard working Victorians. That's thanks to the good work of Victoria Police.
"Our ambulance, paramedics and others have done a first-class job as well and on behalf of all Victorians, I want to thank of every single member of our emergency services family for the dedicated and professional way that they've dealt with the most extreme of circumstances.
"[I] also want to pay special tribute. Every minute, these last couple of hours, we've heard more and more stories of just ordinary Victorians coming to the aid of their fellow Victorians - reaching out, helping, providing assistant, doing the right thing. That does them credit...so we thank each and every member of the public, everyone affected in and around this incident, who has reached out to provide support and care and love to those who have been affected.''
TRANSCRIPT OF POLICE STATEMENT
Acting commander Stuart Bateson:
"What I can confirm is that a male deliberately drove into pedestrians in the Bourke St mall and we currently have three deceased and at least 20 injuries.
"I can confirm that this is connected to an earlier stabbing in Southern Metro region. We have the offender in custody. There is no further threat to the public at this stage.
"I can also confirm that this is not a CT related incident.
"At this present stage, we ask the public to avoid the city. It is going to take us a really long time to process this scene. Our priority at the moment is with the injured and it must be that we give them our attention.
"We'll be able to give you some further information about 5 o'clock (local time) this evening. Members of the public that perhaps witnessed the incident, please log your details with Crime Stoppers."