Update Oct. 20: Police have confirmed to CBC News that the 21-year-old male driver of the stolen vehicle remains in hospital awaiting surgery. No further details about his condition were released. The 28-year-old female passenger has been released from hospital, but remains in police custody.

Read the latest on this story here: Driver who drove toward Calgary parade still in hospital with gunshot wound

Calgary police say national security partners are investigating, but they don't believe there are any links to extremist activity after a driver ignored police barricades and attempted to drive toward a military parade downtown on Saturday.

An officer fired shots in an attempt to stop the vehicle, and Alberta's police watchdog has been called in to investigate.

Sixth Avenue S.W. is closed between Fifth Street and Seventh Street S.W., and Sixth Street S.W. is closed between Fifth Avenue and Ninth Avenue S.W., as of 4:15 p.m. The closure was expected to remain in place for several hours.

At 2:50 p.m. a driver drove through police barricades in the 600 block of 8th Avenue S.W. toward members marching with the 41 Service Battalion Freedom of the City parade, police said.

ALERT: SW Downtown Core, there are several closures in the downtown core due to an ongoing incident. Please avoid the area. <a href="https://twitter.com/hashtag/yyctraffic?src=hash&ref_src=twsrc%5Etfw">#yyctraffic</a> <a href="https://twitter.com/hashtag/yycroads?src=hash&ref_src=twsrc%5Etfw">#yycroads</a> <a href="https://t.co/YoLzX5FIrg">pic.twitter.com/YoLzX5FIrg</a> —@yyctransport

Officers tried to block the car with a patrol vehicle, causing the driver to pull a U-turn and attempt to flee.

An officer then fired shots at the vehicle, which continued to 6th Avenue and Sixth Street S.W. where it collided with a bystander's vehicle before coming to a stop.

He started driving toward me, toward the intersection … that's when [officers] opened fire. - Greg Kucharski, witness.

The driver and the passenger of the vehicle were taken into custody.

The driver, a 21-year-old man, and the passenger, a 28-year-old woman, are in hospital in stable condition. EMS could not confirm if the injuries were caused by gunshots.

Police have shut down several roads after an officer-involved shooting in downtown Calgary. (Terri Trembath/CBC)

Police, pedestrians and the occupants of the bystander vehicle weren't injured, police said.

The officer who fired his gun was a 12-year member of the service.

Car stolen, motive unknown

Photos of the scene show a vehicle at the intersection with extensive damage.

Police said both the vehicle and licence plate were stolen in separate incidents. It's not yet known what the driver's motivation was.

I am glad that the <a href="https://twitter.com/CanadianForces?ref_src=twsrc%5Etfw">@CanadianForces</a> 41 Canadian Brigade Group and everyone in downtown Calgary are safe after the incident today. We are monitoring the situation and are thankful for the quick response from the <a href="https://twitter.com/CalgaryPolice?ref_src=twsrc%5Etfw">@CalgaryPolice</a>. —@HarjitSajjan

The Canadian Armed Forces confirmed on Twitter no army personnel were injured.

Minister of National Defence Harjit Sajjan said he was monitoring the situation and was thankful for the quick response by police.

Greg Kucharski was working nearby and had stopped to listen to the military band when he heard a vehicle revving. He saw it drive past officers who had closed the road for the parade.

"He swerved a couple of times," Kucharski said.

Witness Greg Kucharski points to where he was working when he saw officers shoot at a car that had tried to drive toward a parade in downtown Calgary on Saturday. (Terri Trembath/CBC)

"He rammed the barricade and then he was trying to back up and he started driving toward me, toward the intersection … that's when [officers] opened fire."

Kucharski said he saw other pedestrians duck behind pillars as the shots rang out.

"There was broken windows from where the bullets hit the car. He kept driving … it is pretty crazy to see something like that."

Multiple Calgary Transit routes are being detoured to avoid the road closures.