An attack on an Canadian police officer and a high-speed chase of a van that left four people injured in Edmonton are being investigated as acts of terrorism.
Edmonton police chief Rod Knecht said that officers have one man in custody and they think he acted alone.
Mr Knecht said an Islamic State group flag was found in the car that hit the officer.
The attack began outside a Canadian Football League game at Commonwealth Stadium on Saturday night when police say a white Chevrolet Malibu rammed a traffic control barricade and sent an officer flying into the air.
Mr Knecht said the driver, believed to be 30-year-old, then got out and attacked the officer with a knife before fleeing on foot.
The officer was taken to hospital and treated for non-life threatening injuries while a manhunt was launched.
A few hours later, a U-Haul van was stopped at an impaired driving check on Wayne Gretzky Drive. Mr Knecht said the name of the driver was close to the name of the registered owner of the car that hit the officer.
He said the van then sped off with police in pursuit.
Police said the driver intentionally swerved at pedestrians throughout the chase. Four people were injured by the van, but the extent of their injuries was not immediately known.
The van eventually flipped over near a hotel and a 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,” he said. “It was determined that these incidents are being investigated as acts of terrorism.”
Mr Knecht said Edmonton police are working with the Royal Canadian Mounted Police’s National Security Enforcement Team and other Canadian security agencies.
Alberta premier Rachel Notley said on Twitter that her thoughts are with the injured officer and she is hoping for a speedy recovery.
AP