Witnesses also describe a homeless man talking to the driver and a truck driver preparing to use his vehicle to protect pedestrians. Spotting a stationary oBike on the other side of Swanston Street, the man rushes across the road to retrieve it. Credit:Jean-Daniel Guerin Fabian Wright said a homeless man came up Swanston Street and walked to the car as soon as it stopped in the middle of the Flinders Street intersection. Several videos posted on social media appear to show the two police officers who arrived at the scene within minutes attempting to pepper spray the teenage boy – but his helmet and strong winds made the effort to subdue him ineffective.

After one officer tripped and fell backwards, the teen lunged at him with what appeared to be a large baton, prompting the Critical Incident Response Team to gang tackle and taser the teen, before arresting him. Witness Nik Jerkovic was waiting for a tram on Flinders Street when he heard the screeching of tyres. He saw the driver of the RAV4 do burn-outs for several minutes before a man who appeared to be in his 20s threw an oBike under the four-wheel drive, bringing it to a stop. "That brought the car to a stop, otherwise he would have killed," Mr Jerkovic said. "He was on mission to kill." The 25-year-old kick-boxing instructor and hair stylist said the driver of the RAV4 sat in his vehicle for about 20 seconds before emerging in what he said looked like a cross between army and riot gear – a motorbike helmet, black clothing and knee pads. He said the man had what looked like a large baton and was carrying a small-size camping backpack, covering his whole back.

"It was very, very threatening, especially as it looked like it could have had explosives in it," he said. "It was extremely threatening." Mr Jerkovic said two police officers arrived to the scene within two minutes of the man emerging from his car. Several minutes later about six officers arrived, he said, then a few minutes later about a dozen more officers arrived. Mr Jerkovic said he wanted to take matters into his own hands in the brief moments after the driver emerged from his car and before police arrived. He said the erratic driving and threatening outfit made him worry about a repeat of the Bourke Street rampage in January, when 26-year-old Dimitrious Gargasoulas is alleged to have driven erratically around an intersection before speeding down a footpath, killing six and hospitalising dozens more pedestrians. "I was about to take him straight down. No way was I wanting for it to happen again, for him to be killing all those people," Mr Jerkovic said.

"But he had this backpack on and it looked like it was full of explosives." There is no evidence that the backpack contained anything dangerous. A train driver who narrowly avoided being struck by the vehicle said the threat of explosives and guns and the speedy response of police also stopped him from taking action. "The cops were there pretty much instantly, I was still a fair way away and we weren't sure what was in his hands at first, from that distance," Martyn Fisher said. "With his tactical vest and the backpack – which we don't know what he's got in there.

"It's sort of a 50-50 thing, if things went pear-shaped, then yeah, probably you'd think about intervening, but if he's got an assault rifle, then everyone's running for the hills." Mr Jerkovic said it took about four or five minutes for police to bring the man down. Mr Fisher was having a break with a colleague on Flinders Street when he heard several loud screeches. "At first I thought, here we go, another bad driver in the city," he said. "Then we heard it again … we heard it about three times and we thought, 'what's going on' and then this car goes flying past the tram stop on Fed Square, right in front of us, and does a handbrake turn.

"It just missed us." The 31-year-old Footscray man said the car came within about two metres of him and his colleague. "We noticed he had black, full-faced helmet on, and I thought, 'that's not normal,'" Mr Fisher said. "That's when I realised something a bit out of the ordinary was happening." Mr Fisher said the driver went back down Flinders Street towards the city, narrowly missing a tram, before doing another screeching hand-brake turn.

"Then he came back towards Fed Square and people where just yelling, 'get off the road, there's a lunatic going up and down,'" he said. At that point, several people took action to try and prevent the man from taking lives. Police said the teenage boy from Knoxfield currently remains in custody. Loading - With Neelima Choahan

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