TORONTO - Witnesses described the horrific scenes after a man drove a white van onto the sidewalk along one of Toronto's main thoroughfares, spreading carnage and fear through the country's largest metropolis on Monday (April 23).

Ten people were killed and 15 were injured.

Witnesses said the van struck a man crossing Yonge Street before it jumped the curb near Mel Lastman Square and sped down the sidewalk at 40mph (64kmh), leaving a trail of destruction in its wake, reported New York Times.

Images posted on social media showed bodies lying on a broad, tree-lined sidewalk near a pedestrian plaza, and some of them have been covered with blankets.

John Flengas, acting EMS supervisor for Sunnybrook Health Sciences Center, which said it received seven victims from the scene, told CTV News on Monday that "multiple people were injured, multiple people were deceased."

Flengas described the scene of the episode as "pure carnage" and said there were "victims everywhere."

One witness said the van had mowed down everything in its path: pedestrians, mailboxes, electrical poles, benches and a fire hydrant.

Another, who rushed to help the pedestrian struck while crossing the street, said, "Pieces of the van went flying everywhere."

Reza Hashemi, who owns a video shop on Yonge Street, told the BBC he heard screaming on the other side of the road.

He said the white rental van had repeatedly mounted the pavement and run into people.

"I heard screaming, yelling. I turned back and saw this truck going that way. He was going in and out, back and forth, zigzagging. He just kept on going," said 42-year-old Rocco Cignielli.

There was nothing the customer service worker could do. Emergency services were on the scene quickly, but in some cases their efforts were in vain.

"I saw there were people lying on the ground. I saw they were doing heart compression, and I saw two people dying right here in front of me," Cignielli told Agence France-Presse (AFP), pointing at the bodies.

Nana Agyeman Badu, a 56-year-old taxi driver, saw the van heading south toward central Toronto, where ministers from the G7 world powers were holding a security conference.

Then the van swerved onto the sidewalk.

"I thought maybe he was making a delivery. But I was thinking, 'Why would he drive in the pedestrian walkway like that?' Very fast. Then I saw he had already run over some people," the witness said, according to AFP.

The driver was taken into custody after a dramatic confrontation with police that was captured on video.

"Shoot me in the head," he yelled before he was detained.

Meaghan Gray, a spokeswoman for Toronto police, said authorities received a report at 1.30pm (1.30am Tuesday Singapore time) that a white van had mounted the curb near Yonge Street. The driver was in custody roughly 90 minutes later, she said.

Peter Yuen, deputy chief of the Toronto police service, said "there were a lot of pedestrians out, a lot of witnesses out, enjoying the sunny afternoon" .

"I ask the city of Toronto to pray for our victims and to help the Toronto police service bring this matter to a successful conclusion."

Constable Jenifferjit Sidhu, another police spokeswoman, said that authorities did not know "the cause or reason for the collision."

But Phil Gurksi, who worked for Canada's intelligence service for 14 years, told the New York Times that although police had established no motive for the driver's actions, they appeared to have been intentional.

"What we know is that it was deliberate - this is not an accident," said Gurksi, who retired in 2015 and now runs Borealis Threat and Risk Consulting. "It's not a heart attack."

Hours after the incident, a makeshift memorial was developing at a stone wall just south of Finch Avenue.

Konstantin Goulich, a local resident, appeared with bags of markers and rolls of cardboard from a dollar store.

"Guys please come and write how you're feeling: your wishes for the victims, if you'd like to say something. Every bit of support counts," Goulich said to passers-by.

"If you can't write in English, write in your own language write in Chinese, write in Korean," he said.