The incident took place in broad daylight around 16 kilometres from a conference centre hosting a meeting of G7 ministers, but officials said they had no evidence of a link to the event.
Police arrested a suspect at the scene, but said it was too soon to say whether the attack in Toronto – which has a population of about 2.8 million people – had been deliberate, and if so, what the driver’s motivation might have been.
“This is going to be a complex investigation,” deputy police chief Peter Yuen told reporters. “We have one person in custody and the investigation is ongoing.
“We can confirm for you tonight right now we have nine people that are dead, 16 injured.”
At the scene, a reporter saw at least three bodies under orange sheets and a long stretch of road sealed off with police incident tape.
Dan Cass of Sunnybrook hospital said 10 injured people had been brought in. Two of them were pronounced dead on arrival and five were in critical condition.
Television images showed the man and a police officer facing off, their guns drawn. The suspect eventually surrendered his weapon and was taken into custody.
Vehicle attacks have been carried out to deadly effect by extremists in a number of capitals and major cities, including London, Paris, New York and Nice, heightening fears of a deliberate ramming.
Canada’s minister for public safety, Ralph Goodale was asked at the G7 meeting whether the government had received any threats or information to suggest that the talks might be targeted.
“No, not to my knowledge,” he said.
Standing alongside him, Canada’s foreign minister Chrystia Freeland said the G7 meeting would continue as planned, with officials discussing ways to secure democratic societies from foreign interference.
“The work of the ministers obviously goes on. This is a very sad day for the people of Toronto and the people of Canada,” she said.
Officers were called to the scene – on Yonge St at the corner with Finch Ave – at about 1:30pm (12:30am Thai time), police said.
A white rental van with a dented front bumper was stopped on the sidewalk of a major intersection, surrounded by police vehicles.
“He was going really fast,” witness Alex Shaker told CTV television.
“All I could see was just people one by one getting knocked out, knocked out, one by one,” Shaker said. “There are so many people lying down on the streets.”
Another witness, Jamie Eopni, told local Toronto television station CP24: “It was crashing into everything. It destroyed a bench. If anybody was on that street, they would have been hit on the sidewalk.”
Canada has only rarely been the scene of terror attacks.
In October, a man stabbed a police officer in the western city of Edmonton before slamming his van into a group of pedestrians, injuring four people.
And in Quebec in October 2014, a Canadian man ran over two soldiers in a parking lot with his car, killing one of them. The driver was shot dead by police when he attacked them with a knife.
In March 2016, a Canadian who claimed to have radical Islamist sympathies attacked two soldiers at a military recruitment centre in Toronto.