Two men have been arrested after a car was driven into pedestrians in Australia's second largest city, in what officers have called a "deliberate act".
Police said 14 people were injured - several critically - when the white SUV was driven at crowds outside Flinders Street station in Melbourne just after 4.30pm (5.30am GMT) on Friday.
The area is one of Melbourne's busiest intersections and was busy with Christmas shoppers at the time of the incident.
Commander Russell Barrett declined to comment on whether the incident was terror-related, adding the motivation was unknown.
He said: "At this stage we believe it is a deliberate act, however we do not know the motivation and it is still the early stages of the investigation."
Images from the scene showed a number of people receiving medical attention, while a white Suzuki SUV appeared to have crashed to a stop.
A woman called Sue told 3AW radio: "As it (the car) approached this intersection... it just mowed everybody down, people were flying everywhere."
Social media images appeared to show a young man in jeans and a T-shirt being arrested by three police officers on the steps of the station, although it was unclear if he had been in the car.
Sky News said the driver of the SUV was of Middle Eastern appearance and that he was wrestled to the ground and handcuffed following the crash.
Australian prime minister Malcolm Turnbull called it a "shocking incident" adding: "Our thoughts and prayers are with the victims and the emergency and health workers who are treating them."
Meanwhile, the England cricket squad and management - who are in Melbourne for the Boxing Day Ashes Test - are all safe, the England and Wales Cricket Board said.
A brief statement read: "Following the Flinders Street incident in Melbourne, all players and management have been accounted for and are safe."
The fourth Test is scheduled to get under way on Tuesday at the Melbourne Cricket Ground, around a mile from the scene of Thursday's incident.
Lachlan Read told the Herald Sun the whole incident lasted about 15 seconds.
"It was bang, bang, bang. It was just one after the other.
"The last bang the car stopped," the 20-year-old said. "There were bodies on the ground and people running up to them - it was mayhem.
"It is definitely something you don't expect to see on Flinders Street."
Elton Hindoli, who works at an off licence by the scene of the incident in Elizabeth Street, told the Herald Sun that a man who was pulled from the car appeared to be unconscious.
"A girl came into the shop and she was very upset," he said.
"She said a guy in a big car had hit about six people.
"It wasn't clear if the driver was hitting them on purpose or not.
"He hit the people then crashed into the tram area in the middle of the road."
The incident follows a spate of attacks in major cities in Europe and the US in which terrorists have used vehicles as a weapon again innocent people.
Eighty-six people were killed in Nice in July 2016 when a lorry was driven into crowds celebrating Bastille Day.
Twelve people died in December last year when a truck was driven at crowds at a Christmas market in Berlin.
Four pedestrians and a police officer were killed by Khalid Masood in the Westminster Bridge attack in March.
In June, eight people were killed and 48 injured when three terrorists ploughed into pedestrians on London Bridge then went on a knife rampage in Borough Market.
Thirteen people were killed when a van was driven down Barcelona's Las Ramblas in August, and in October, eight died in a truck attack in New York.