A car has hit pedestrians on Melbourne’s Flinders Street resulting in the arrest of the driver - who police say has a history of mental illness.
The driver, 32, has been arrested after a car ploughed into 19 pedestrians on Flinders Street.
A second man, 24, was initially arrested but police have since said he has no links to the incident.
Victoria Police are currently attending the scene of the incident between Elizabeth Street and Swanston Street.
Police officers will remain at the scene for the foreseeable future - at least until 7am tomorrow.
Police say the driver of the vehicle, was arrested by an off-duty police officer.
Police said the driver, an Australian citizen of Afghani descent, had a history of mental illness and did not have links to terrorism. He was taken to hospital and remains under police guard.
"The officer sustained shoulder and hand injuries during the arrest and has been conveyed to hospital," a police spokesman said on Thursday night.
Police said the driver was the only person inside the vehicle during the incident.
Nineteen pedestrians were injured in the incident and all were taken to hospital. Two others were also treated for non-collision related injuries.
Among those injured were five men, six women and one four-year-old boy.
Victorian Premier Daniel Andrews said the incident was an 'act of evil and cowardice'.
He praised police for being on scene within seconds of the incident occurring.
“Stay safe, check on your loved ones and thank you to our brave emergency services,” he tweeted earlier in the day.
Commander Russell Barret told media earlier today that police suspected the act was ‘deliberate’ however the motive was unclear.
“Police will continue to have a strong presence in the Melbourne CBD tonight,” Commander Barrett said.
“People may have items and vehicles within the crime scene. At this stage, they will not be able to be retrieved until the crime scene is reopened.
“We understand that this has been a very traumatic event… and there will be witnesses, victims and family members affected.”
“We believe based on what we have seen that it is a deliberate act.
Officer Creina O’Grady said police have saturated the CBD area following the incident.
“The incident occurred when the vehicle struck a number of pedestrians in front of Flinders Street Station just after 4.30pm,” she said.
The extent of the pedestrians' injuries is unknown at this stage but includes a pre-school aged child with head injuries.
Police are asking any witnesses to go to the Melbourne West Police Station at 313 Spencer Street, Melbourne and all vehicular and pedestrian traffic have been asked to avoid the area.
Emergency crews rushed to the scene to help attend to the injured.
Ambulance Victoria said in a statement: “Paramedics were called to a report of pedestrians hit by a car at the corner of Elizabeth Street and Flinders Street at 4.41pm this afternoon. Paramedics are on scene.”
Melbourne city’s public transport system went into lock-down after the incident.
"Due to a major incident at the intersection of Elizabeth and Flinders Streets, passengers are advised to defer travel through Flinders Street Station," Metro Trains tweeted.
"Please interchange for services at Southern Cross and City Loop Stations."
All Swanson Street trams between stop 11 Collins St and Stop 14 Arts Precinct were cancelled.
Prime Minister Malcolm Turnbull praised emergency service workers who assisted at the scene.
“As our federal and state police and security agencies work together to secure the scene and investigate this shocking incident, our thoughts and prayers are with the victims and the emergency and health workers who are treating them,” he wrote on Twitter.
'It just mowed everybody down': Witness
Witnesses told the Herald Sun they saw a white Suzuki hit a number of pedestrians crossing over Flinders St, one of Australia’s busiest intersections.
It's understood there was up to 60 people crossing the road at the time - the area was packed with people doing their Christmas shopping.
"The driver was speeding, it was horrific, I can't believe it," one witness claimed.
"There was people's bodies on the ground. I didn't know what to think (sic).
Witness Sue who works at a doughnut shop in the area told 3AW she saw a white car approach the intersection where a lot of people were crossing the street at the time.
‘We turned to the left… we see this white car as it approaches the intersection – it just mowed everybody down… people are flying everywhere,” she said.
“Then we hear this thump…thump… the car must’ve hit the tram stop in the middle.”
Victoria Police has urged the public to share photos or images of the incident to assist with their investigation here: http://australiauploadserviceweb.cloudapp.net/