Canadian authorities have named the suspect in the Edmonton terror attack as Somali refugee Abdulahi Hasan Sharif, a known extremist investigated by police in 2015.

Edmonton Police Service has also released a graphic video of the initial phase of the attack, in which Sharif ploughs a car through a police checkpoint near the Commonwealth Stadium and sends an officer flying through the air, before exiting the vehicle and stabbing him multiple times.

WARNING: Disturbing images.

Edmonton police released security video showing the terror attack where an officer was rammed with car, stabbed pic.twitter.com/UlvB8TBdjI — Globalnews.ca (@globalnews) October 1, 2017

Sharif’s past extremism was revealed by the Royal Canadian Mounted Police (RCMP), CTV reports.

“We can confirm that in 2015, a complaint was filed with the Edmonton Police Service, around reports being made that the suspect was espousing extremist ideology,” admitted RCMP Assistant Commissioner Marlin Degrand. “At the end of that exhaustive investigation, there was insufficient evidence to pursue terrorism charges or a peace bond.

“Further, the suspect was not actually deemed, at that time, to pose a threat to the security of Canada.”

Edmonton Police Chief Rod Knecht said charges have not been laid yet, but confirmed that Sharif has been arrested for participation in a terrorist act, commission of an offence for a terrorist group, five counts of attempted murder, dangerous driving, criminal flight causing bodily harm, and possession of a weapon for a dangerous purpose.

After his initial attack outside the sports stadium, Sharif later appeared in a rented U-Haul van with up to fourteen cruisers in hot pursuit.

The 30-year-old refugee slammed into at least four pedestrians during the chase, before his vehicle somehow ended up on its side.

Canadian prime minister Justin Trudeau, who campaigned for office pledging he would fight for the right of terrorists to keep their citizenship, responded to the Edmonton attacks with a statement asserting: “We know that Canada’s strength comes from our diversity”.

He also tweeted: “We’ll never let violent extremism win” — drawing sharp criticism from some quarters.

“It is winning, mate. And every day it’s winning a little more,” responded Jordan Peterson, a Professor of Clinical Psychology at the University of Toronto, who has become something of an icon among young conservatives and free speech advocates.

Follow Jack Montgomery on Twitter: @JackBMontgomery