At least three people have been killed and 20 injured in a high-speed car chase through the centre of the Melbourne CBD that saw numerous pedestrians run down and gunshots fired, ending with a dramatic arrest on Bourke Street.
Police sources are warning that multiple people could have suffered fatal injuries.
A maroon-coloured sedan was being pursued by police around 1:40pm when it crossed into the pedestrian-only section of Bourke Street Mall, driving erratically along the popular shopping strip.
Witness Rebecca Russo told Fairfax Media she saw three people hit by the car as it sped through the mall with police in pursuit.
"We were just standing on Bourke Street, and we heard a bit of a crash coming from the mall. I saw a maroon car driving up the pedestrian path on the Flinders Street side.
"People were running out of the way, they were going very, very fast. I saw him hit a few people. I saw bodies flying into the air."
Emergency services have reported they are treating of at least 20 at multiple incident accident scenes.
"All we could see is just the car and carnage, people were flying everywhere," witness Hank Kerr said in a video posted to Twitter: "Every few metres there's someone badly injured."
The vehicle then crossed over Elizabeth Street, heading west along Bourke Street near the corner of William Street when other witnesses reported hearing gunshots.
Shortly afterwards, armed police surrounded the maroon car and dragged a single occupant from the vehicle.
He was restrained and stripped down to his underwear, according to video and photos posted by observers in nearby buildings.
The vehicle is heavily damaged, with the hood crumpled in and a smashed windscreen.
Video footage taken outside Flinders Street Station shows a maroon car doing "burnouts" in the middle of the intersection of Flinders Street and Swanston Street before speeding north towards Bourke Street Mall.
The Royal Childrens Hospital, which is treating injured from the incident, warned its emergency facility is "very busy".
"If planning to bring your child w/ a less urgent condition, but can see GP or local hospital,we'd appreciate it," the RCH said on Twitter.