Canadian police arrested a man early on Sunday suspected of stabbing an officer and deliberately ramming pedestrians during a high-speed chase in a rented truck, injuring four in what authorities were calling an "act of terrorism".
The incident took place outside a Canadian Football League game at Edmonton's Commonwealth Stadium on Saturday night.
The suspect's vehicle struck the officer, "sending him flying 15 feet through the air", police said.
After the attack on the officer, police began a manhunt, and the suspect was pulled over while driving a U-Haul truck.
Edmonton Police Chief Rod Knecht said officers have one person in custody and think he acted alone, but are not ruling out that others may be involved.
He confirmed that a Daesh flag had been seized from the vehicle connected with the attack on the police officer.
Two hours later just after 11 p.m. Police were called to 109 Street and Jasper Avenue as witnesses seen people get run over by a UHaul van and one person was loaded into an ambulance.
The U-Haul eventually overturned near a downtown hotel and police dragged the driver out of the truck.
Police believe the 30-year-old culprit surfaced again behind the wheel of a moving van at a checkpoint. Their conditions were not immediately known, the police chief said.
The suspect peeled out with dozens of police cars in pursuit.
Police believe the suspect, who was known to police, acted alone but are not discounting that he had accomplices. The driver took off again, prompting officers to give chase to the large U-Haul van.
The name of the suspect was not released.
Alberta premier Rachel Notley said on Twitter that her thoughts are with the injured officer and she is hoping for a speedy recovery. They said they now believe the suspect acted alone, but haven't ruled out the possibility of others being involved. "Grateful for our first responders".
"The investigation is in its very early stages and we are urging Edmontonians to be vigilant and aware of their surroundings".