Witnesses have described their horror at seeing bodies "flying" into the air as a car drove erratically through Bourke Street Mall in Melbourne this afternoon.
It comes as CCTV footage shows terrified pedestrians running for safety as a car is seen flying down the street.
One woman, Renee, who was waiting nearby and facing the window of Bourke Street, told news.com.au she heard a "loud thud" as three people were mown down in front of her eyes.
"I saw the car on the footpath and I saw the people out of the corner of my eye fly in the air. "There were three or four contorted bodies on the ground."
"There was a girl standing right in front, the car had missed her. She looked around, saw the bodies, looked down the street, then just started screaming."
One man, Hank Kerr, told The Guardian he saw "people flying everywhere" as he sat on the tram when he saw the incident unfold.
"We saw this car on the footpath," he told journalist Calla Wahlquist.
"There were people jumping out of the way and people being hit. All we could see is the car and carnage. People were flying everywhere. It was shocking to see."
A number of people have been injured in Melbourne's CBD amid reports of shots fired and a police car chase in Bourke St.
It's feared at least one pedestrian has been hit in Bourke Street Mall by a car driving erratically. Some reports suggest as many as 12 people could have been injured.
Police could only say they were aware a "number of people were injured" in the CBD, but could not immediately give details.
American tourists Michelle and Daryl told Sky News they saw at least four or five people injured and heard at least five gun shots as they ducked for safety.
I've only managed to speak with her briefly, but she is extremely fortunate to be unijured. Understandably, she is very shaken. #Melbourne— Domenic Stephen (@domenicstephen) January 20, 2017
"We were coming up the street and we saw the pram down from up the street," Michelle said. "(We took cover) then we came back out and saw all the people injured on the side walk. I saw four or five (people injured). There were police everywhere. They drew their weapons right away.
Was in Bourke St Mall when the driver who caused the police operation in #Melbourne went past. Shirtless, cigarette hanging out of his mouth— Ellen (@punzikstan) January 20, 2017
"(I was) stunned when I saw them drawing their weapons. People started screaming. We ran the opposite direction of police. People started screaming."
Another witness, known as Chris, told Sky News there was "just a hell of a lot of blood.
"I feel pretty moved and quite sick. It's a horrible thing to have had happened."