Canadian police say a man driving a white car struck a police officer and stabbed him multiple times outside a football stadium Saturday.

Hours later, police say, the same man – this time driving a U-Haul truck – was pulled over a few miles away, drove off and struck four pedestrians.

The related attacks Saturday night in Edmonton, the capital of Alberta, Canada, are being investigated as an act of terrorism, Edmonton Police Chief Rod Knecht said during a news conference early Sunday.

He said an Islamic State flag was found in the passenger seat of the white Chevrolet Malibu the suspect was driving that night.

The suspect, a 30-year-old Edmonton man who has not been named, has been arrested. Knecht said the man acted alone, but investigators were not ruling out the possibility that others may be involved.

The officer’s injuries were not critical, Knecht said, adding that he does not have any information about the other victims’ conditions.

The attacks began just after 8 p.m. during a football game at the Commonwealth Stadium. The officer was standing behind barricades and facilitating traffic outside the venue when the man rammed his Chevrolet Malibu into the barricades and struck the officer, sending him 15 feet into the air, Edmonton police said.

The man then got out of his car, “viciously” stabbed the officer with a knife and ran away, police said.

Less than four hours later, just before midnight, a U-Haul truck was pulled over about four miles away. An officer recognized that the driver’s name was similar to that of the registered owner of the Chevrolet Malibu, police said. The man immediately drove away, leading officers on a chase toward downtown Edmonton as he deliberately hit pedestrians on the way, police said. The chase ended when the truck flipped over and landed on its side.