Police said two men had been arrested, and that "at this stage, we believe it is a deliberate act."
A car mowed down pedestrians on Flinders Street in the Australian city of Melbourne, and the "extent of injuries" is still unknown, Victoria Police said.
The Associated Press, a news agency, said 14 people were injured. One of them, police confirmed, was a pre-school aged boy with head injuries. He and another person were in critical condition.
Police said two men had been arrested, and that "at this stage, we believe it is a deliberate act."
Prime Minister Malcolm Turnbull said Australians' thoughts and prayers were with the victims.
Victoria Police also asked witnesses to go to Melbourne West Police Station at 313 Spencer Street, and people who have any useful multimedia evidence to upload them at australiauploadserviceweb.cloudapp.net.As our federal & state police & security agencies work together to secure the scene and investigate this shocking incident our thoughts & prayers are with the victims & the emergency & health workers who are treating them. https://t.co/JkUM9TuIQe
- Malcolm Turnbull (@TurnbullMalcolm) December 21, 2017
Video of first arrest made on #FlindersSt in #Melbournepic.twitter.com/7OFxGWgfGe
- anomie (@AnimeRenaissanc) December 21, 2017
There's no word yet on whether this was an act of terrorism, but we do know from an article in the Mirror, which says - citing reports - that the terrorist group ISIS had called for attacks on Christmas markets in Europe.
That article cited an Epoch Times report on an image obtained by a darknet intelligence company, which shows a man - covered and hooded in black cloth - standing behind Santa Claus, with a hand behind his neck. "Soon on your holidays," reads a message, written in English, French and German.
According to the Epoch Times report, the image is of Regent Street in London.
WATCH |Commander Russel Barrett speaks to reports after the Flinders Street incident.
Media conference regarding the Flinders Street incident with Commander Russell Barrett. pic.twitter.com/j7zx0V5fYQ
- Victoria Police (@VictoriaPolice) December 21, 2017