Policemen investigate the site where a van struck pedestrians in Toronto. Picture: Zou Zheng/Xinhua

Toronto - A driver deliberately plowed his white Ryder rental van into a lunch-hour crowd in Toronto on Monday, killing 10 people and injuring 15 along a roughly 1.6-km stretch of sidewalk thronged with pedestrians, police said.

Although the attack had the hallmarks of recent deadly vehicle assaults by Islamic State supporters in the United States and Europe, federal officials said it did not represent a larger threat to national security.

Toronto Police Chief Mark Saunders identified the suspect as Alek Minassian, 25, who he said had not previously been known to authorities. Police, who quickly arrested Minassian, do not know his motives.

"The actions definitely looked deliberate," Saunders told a late-night news conference close to the site of the incident in the northern section of Canada's biggest city, noting the van had been driven along sidewalks.

The brutal incident - which Prime Minister Justin Trudeau called a "tragic and senseless attack" - was one of the most violent in recent Canadian history.

Federal Public Safety Minister Ralph Goodale, standing next to Saunders, said: "There would appear to be no national security connections."

Global Television said Minassian would appear in a Toronto court at 10am ET (1400 GMT) on Tuesday.

The attack shook the usually peaceful streets of Toronto, a major tourist destination. The city, which has a population of 2.8 million, recorded 61 murders last year.

"This kind of tragic incident is not representative of how we live and who we are," Toronto Mayor John Tory told reporters. Downtown Toronto's iconic CN Tower, which is normally lit up in the evening, went dark on Monday evening.

The drama started just before 1.30pm when the driver steered his vehicle into the crowds.

A man who gave his name as Ali told CNN he saw the van and that the driver appeared to have been targeting people.

"This person was intentionally doing this, he was killing everybody," the man said. "He kept going, he kept going. People were getting hit, one after another."

The street was soon covered in blood, empty shoes and bodies.

Video footage shot by a bystander showed police arresting a suspect at the scene as he shouted: "Kill me" and pointed an unidentified object at a policeman.

The officer replied, "No, get down."

When the suspect said, "I have a gun in my pocket," the officer responded: "I don't care. Get down."

The tragedy struck as Canada was still recovering from the shock of a highway crash in Saskatchewan earlier this month that killed 16 people on a bus carrying a junior hockey team.

A police officer stands guard near the site where a van struck pedestrians in Toronto. Picture: Zou Zheng/Xinhua

'TRAGIC AND SENSELESS ATTACK'

"It was with great sadness that I heard about the tragic and senseless attack that took place in Toronto this afternoon," Trudeau said in a statement. "We should all feel safe walking in our cities and communities."

Last October eight people died in New York when a man driving a rented pickup truck mowed down pedestrians and cyclists on a bike path.

The Islamic State militant group encourages its supporters to use vehicles for attacks.

Last month, a former Canadian university student pleaded guilty to killing six men praying in a Quebec City mosque in January 2017.

In September, a Somali refugee was charged with attempted murder over allegations he ran down four pedestrians with a car and stabbed a police officer outside a sports stadium in Edmonton, Alberta.

Trudeau was due to address the media at 0825 ET (1225 GMT) on Tuesday, his office said.

In a statement, the White House press secretary said Washington "pledges to provide any support Canada may need".

Monday's incident occurred about 30km from the site where Toronto is hosting a meeting of Group of Seven foreign ministers from Canada, the United States, Britain, France, Germany, Italy and Japan, but had no noticeable effect on that event's security.