A car and knife attack on a police officer and a high-speed chase of a moving van that left four people injured appear to be the work of a single suspected terrorist, Canadian authorities said.
Edmonton police chief Rod Knecht said officers took the suspect, later described as a 30-year-old Edmonton man, into custody and he is believed to have acted alone.
Mr Knecht said an Islamic State group flag was found in the car that hit the officer, and Canadian prime minister Justin Trudeau called it a terror attack.
“To the best of our knowledge, this was a lone wolf attack,” Edmonton mayor Don Iveson said.
The incident took place outside a Canadian Football League game at Edmonton’s Commonwealth Stadium on Saturday night.
Police released video showing a white Chevrolet Malibu ramming into a police officer standing in front of his cruiser.
The officer was sent flying in the air while the Malibu crashes into the police car.
The driver then gets out and appears to stab the officer.
“Seeing the video is very upsetting because of the level of violence and level of intent,” Mr Iveson said.
Mr Knecht said the suspect fled on foot after stabbing the officer.
The officer was taken to a hospital and treated for non-life-threatening injuries while a manhunt was launched, and Mr Knecht said his condition was “not critical”.
A few hours later, a U-Haul van was stopped at an impaired driving checkpoint north of downtown, on Wayne Gretzky Drive.
Mr Knecht said the name of the driver was similar to the name of the registered owner of the car that hit the officer.
He said the van then sped off toward downtown with police in pursuit.
Police say the vehicle swerved at pedestrians at crosswalks throughout the chase. Four people were hurt, but the extent of their injuries was not immediately known.
The van eventually flipped near a downtown hotel and the suspect was arrested. Mr Knecht said the man was known to police but did not release his name.
“It is believed at this time that these two incidents are related,” Mr Knecht said.
“It was determined that these incidents are being investigated as acts of terrorism.”
Mr Knecht said Edmonton police were working with the Royal Canadian Mounted Police’s national security enforcement team and other Canadian security agencies.
He advised the public to remain vigilant and observant of their surroundings.
Witness Pat Hannigan told reporters he saw police pull a man from the windshield of the toppled van and estimated that 30 police cars had been chasing it.
Austin Elgie, manager of The Pint bar just west of the downtown core, also saw the van zoom by with police giving chase.
It “peeled” into an alley where people were smoking, he said.
“It was crazy,” Mr Elgie said. “It just came around the corner, ripping.
“I thought at first he was pulling over for the cops coming by, but he was clearly the one they were chasing.”
Mr Elgie said the van hit a man who was a bar customer.
“I have a registered nurse on my bar team, and I grabbed her and had her look after the guy until the ambulance came,” he said.
“He was breathing and we got him in the ambulance and he was still breathing.”