By Agence France-Presse
The crime spree began Saturday evening outside a football stadium in the western city of Edmonton and ended hours later with a high-speed chase in which the driver of a rented truck plowed into pedestrians, police said.
The driver, described by police as a 30-year-old Edmonton resident, was apprehended after the truck flipped onto its side.
"Currently, we believe this is an individual who acted alone, although the investigation is in its early stages," Edmonton police chief Rod Knecht said.
Prime Minister Justin Trudeau called the incident a "terrorist attack," and urged Canadians to be vigilant.
"I am deeply concerned and outraged by this tragedy," he said in a statement.
"While the investigation continues, early reports indicate that this is another example of the hate that we must remain ever vigilant against," he said.
Trudeau said the Royal Canadian Mounted Police and the country's Integrated National Enforcement Team had joined the Edmonton police in its investigation.
"We cannot -- and will not -- let violent extremism take root in our communities. We know that Canada's strength comes from our diversity, and we will not be cowed by those who seek to divide us or promote fear," he said.
- Police officer hit -
At approximately 8:15 pm Saturday (0215 GMT Sunday) a man in a speeding white Chevy Malibu crashed through police barricades outside an Edmonton stadium where a Canadian Football League game was being played.
The car struck a police officer standing in front of his patrol car, "sending him flying 15 feet through the air."
"A male, believed to be 30 years of age, then jumped out of his vehicle and began viciously stabbing the officer with a knife, as a struggle ensued," the police statement said.
The suspect then fled on foot and the police officer was rushed to a hospital.
- Rented truck -
Just before midnight, police pulled over a rental U-Haul truck and noticed that the name on the driver's license was similar to that of the name under which the white Malibu was registered.
The man in the truck then took off toward downtown Edmonton, according to the police account.
"During the chase, the U-Haul truck deliberately attempted to hit pedestrians in crosswalks and alleys," it said.
"Currently, it is believed four pedestrians were struck by the truck and transported to hospital with multiple injuries," it said.
The chase ended when the truck flipped on its side, and the driver was arrested.
The incident was reminiscent of similar vehicle attacks by jihadists in Barcelona, London, Nice, Berlin and Stockholm.
In 2014, a Muslim convert ran over two soldiers in a parking lot in Saint-Jean-sur-Richelieu, Quebec, killing one of them. The assailant was shot to death after he tried to attack a police officer with a knife.
That incident came just two days before a soldier guarding the National War Memorial in Ottawa was shot and killed by a Canadian Muslim in an incident that spilled into the nearby Canadian parliament before he, too, was killed by police.
Several Canadians have joined the ranks of Islamic State over the past five years, and others have been intercepted and jailed on terrorism charges under a law made tougher after the attack in Ottawa.
In March 2016, a Canadian who said he was acting on orders of Allah attacked two soldiers with a knife at a recruitment center in Toronto.
Canada is a member of the international coalition fighting IS in Iraq and Syria. Although it has withdrawn its combat aircraft from coalition operations, it still has special operations forces and trainers on the ground in Iraq.