Three people, including a young child, have died after a car deliberately hit pedestrians in central Melbourne, police say.
At least 29 people were injured, among them a baby who is in a critical condition after the car hit a pram.
Police say they rammed the car, shot the driver in the arm and arrested him.
They say the incident was not terror-related, but is believed to be linked to a stabbing in Melbourne's south-east early on Friday.
The car ploughed into the pedestrians in the Bourke St Mall, a busy shopping area, just before 14:00 (03:00 GMT).
Footage broadcast on local media showed a maroon car driving in circles in front of nearby Flinders Street railway station.
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A witness told the BBC she saw pedestrians try to get out the way as the car mounted a footpath.
"It hit a few people there outside the offices and convenience store and sent them flying into the air, then kept driving," the witness said.
"It hit some more further up the path. I didn't know what was happening at first. People were screaming and there was a lot of sound and dust - I thought a building was coming down."
Another witness, Sharn Baylis, estimated the car was travelling at 60km/h (37 mph) "in a straight line".
"It was such an enclosed busy area," she told ABC.
Witness Maria Kitjapanon told Melbourne's Age newspaper that the car was rammed by a police car and that about 10 police surrounded the car, with guns drawn, and fired into the car.
"Then they dragged someone out via the passenger side, then all 10 of them sat on top of him," she said.
EPA
Police say the same man was involved in an an attack on his brother in the early hours of the morning in a Melbourne suburb.
Its believed he then went on to take a woman hostage in the car. She was released before the driver proceeded to the city centre and started to hit pedestrians.
The police say the man is known to them, and has a long history of family violence, drug issues and mental health problems.
He was also charged at the weekend in relation to an assault.
The three people who died have not been named, but police say they were a man and woman in their 30s, and a young child.
The injured baby was three months old. Also among the injured were a two-year-old who is in a serious condition, and children aged nine and 12.
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The Premier of Victoria, Daniel Andrews, said the emergency services had "done us proud" in their response to what he described as an evil criminal act".
"Our hearts are breaking this afternoon," he said.
He also praised people in the city who had "reached out to provide support and care to strangers".
Lord Mayor Robert Doyle said he was standing outside Melbourne Town Hall when he saw the car drive "at speed" towards Bourke St Mall.
"It is very difficult to believe that these sorts of things can happen right in front of you in the middle of our city," he said in a video posted online.
"Spare a thought particularly for those families - the loved ones of those affected - and let's try and take care of each other."
The Australian Open tennis event, being played about 2km (1.2 miles) away, was unaffected, police said.
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