Suspect arrested in officer's stabbing in Canada by man with ISIS flag on dashboard: Police

— -- A man who allegedly attacked a police officer in Edmonton, Canada, with a knife and then injured four civilians with his vehicle as he attempted to flee has been arrested, but not yet charged, police officials said

The man was identified as a Somali refugee who was interviewed by police in 2015 regarding a complaint that he was exposing radial ideology, but at the time it was deemed he was not a threat to Canada, police said.

Although police said they were investigating the incident as an "act of terrorism," that said it appears that the suspect was acting alone. They were investigating many leads, however, and conducting searches at several locations around the city, police said.

Police said a man driving a car with an ISIS flag on its dashboard rammed "at a high rate of speed" into a police barricade where an officer was directing traffic outside an Edmonton Eskimos Canadian Football League game at about 8:15 p.m. local time Saturday evening in Alberta province.

The suspect's car struck the officer, "sending him flying 15 feet through the air," police said.

The 30-year-old suspect then exited the vehicle, a white Chevrolet Malibu, and used a knife to stab the officer, police said.

The officer was stabbed multiple times, but police reported his injuries are not life-threatening.

The suspect then fled the scene on foot and managed to escape police.

Two hours later, police pulled over the driver of a U-Haul truck at a police checkpoint in the city and asked for the person's license. The officer noticed the name was similar to the owner of the Chevy Malibu, at which point the U-Haul driver fled the scene with police in pursuit.

According to police, the U-Haul driver headed toward downtown Edmonton and "attempted to deliberately hit pedestrians in the crosswalk." Police say "it is believed four pedestrians were struck by the truck and transported to hospital with multiple injuries."

During the chase, the U-Haul flipped on its side on Jasper Avenue, a main thoroughfare in downtown Edmonton, and authorities managed to apprehend the individual, police said.

Photos posted on social media of Jasper Avenue showed the U-Haul flipped on its side in the middle of the street.

The Edmonton Police Service said the driver rammed the officer outside Commonwealth Stadium. Police confirmed the ISIS flag said to have been on the car dashboard as evidence, but would only say it was part of the investigation.

"Based on evidence at the scenes and the actions of the suspect, at 12:38 a.m. today it was determined that these incidents are being investigated as acts of terrorism," said Rod Knecht, Edmonton police chief.

Knecht said in a statement, “Currently, we believe this is an individual who acted alone, although the investigation is in its early stages."

We are urging all Edmontonians to be vigilant and aware of their surroundings," Knecht said. "Please contact police immediately if you see or hear anything out of the ordinary or unusual.”

Police said that the officer who was injured was “safe and recovering.” A police spokesman told ABC News that the officer was out of the hospital. The spokesman did not give the conditions of the other four people who were injured.

The U.S. Department of Homeland Security said in a statement that it is closely monitoring the situation and will provide support and assistance to Canadian officials. The White House released a statement Sunday afternoon condemning the attacks, and said that U.S. law enforcement authorities are in touch with Canadian counterparts to offer assistance with the investigation.

ABC News' Christopher Donato and Dominick Proto contributed to this report.