Ten people have died and 15 others have been hospitalised after a vehicle was driven into pedestrians on a busy street in Toronto.
The incident happened on central Yonge Street, shortly before 1.30pm local time.
A 25-year-old suspected named Alek Minassian has been arrested, police said.
Authorities say they had no previous information on the suspect, and any motive is unknown.
However, police chief Mark Saunders said the erratic driving suggests the incident was deliberate.
He explained: "At some points [the van was driving] on sidewalks, at some points driving southbound in northbound lanes... so it's very clear, just from a general perspective, to say the actions definitely look deliberate."
Canadian Prime Minister Justin Trudeau said: “It was with great sadness that I heard about the tragic and senseless attack that took place in Toronto this afternoon.
"On behalf of all Canadians, I offer my heartfelt condolences to the loved ones of those who were killed, and my thoughts for a fast and full recovery to those injured."
He added that the actions of first responders "no doubt saved lives and prevented further injuries".
Canada's public safety minister Ralph Goodale, who visited the scene of the incident, added it appeared there was 'no national security connection'.