Van rams traffic barricade hitting policeman before high-speed chase in Canada 'terror attack'

A vehicle rammed into a barricade at a Canadian Football League game

A toppled U-Haul truck in Edmonton, Canada at the scene of terrorist incident (Twitter @ZoeHTodd)

Canadian police said attacks on an officer outside a football game with a car and knife and a high-speed chase of a removal lorry which left four people injured in the western city of Edmonton, Alberta, are being investigated as acts of terrorism.

Edmonton Police Chief Rod Knecht said that officers took a suspect in custody and they think he acted alone. Knecht said an Isis group flag was found in the car that hit the officer. They later described him as a 30-year-old man living in Edmonton.

Later the force confirmed the man was a Somali man seeking asylum in Canada.

The attack began outside a Canadian Football League game outside 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 15 feet.

Officer Knecht said the driver, believed to be 30 years old, then got out and attacked the officer with a knife before fleeing on foot.

The officer was taken to a hospital and treated for non-life threatening injuries while a manhunt was launched. "It's not critical," Officer Knecht said of the injuries.

A few hours later, a U-Haul van was stopped at an impaired driving check stop north of downtown on Wayne Gretzky Drive. OfficerKnecht 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 U-Haul then sped off toward downtown with police in pursuit.

Police say the U-Haul intentionally swerved at pedestrians at crosswalks throughout the chase. Four people were injured by the van, but the extent of their injuries was not immediately known.

The van eventually flipped near a downtown 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," Officer Knecht said. "It was determined that these incidents are being investigated as acts of terrorism."

He added that Edmonton police are working with the Royal Canadian Mounted Police's National Security Enforcement Team and other Canadian security agencies. Officer Knecht told the public to remain vigilant and observant of their surroundings.

Officer Knecht said police didn't call off the chase of the U-Haul due to the seriousness of the crime.

Witness Pat Hannigan told reporters that he saw police pull the man from the windshield of the toppled U-Haul.

He said 30 police cars were chasing the U-Haul.

Alberta Premier Rachel Notley said on Twitter that her thoughts are with the injured officer and she's hoping for a speedy recovery.

Associated Press ​