The suspect, with whom police were familiar from past terror investigations, was identified as Aaron Driver, said Mike Cabana, deputy commissioner of federal policing for the Royal Canadian Mounted Police.
Driver was killed Wednesday outside his sister's home in Strathroy, Ontario, just after entering a cab around 4:30 p.m., Cabana said. Police engaged Driver, who detonated an explosive device inside the cab, injuring the driver, he said.
It's unclear if Driver, who was wearing a backpack, was carrying the explosive on his body or elsewhere, said RCMP Assistant Commissioner Jennifer Strachan, commanding officer of the Ontario division.
Police believe Driver was planning to stage an attack within 72 hours, Cabana said.
FBI and RCMP had been monitoring Driver since at least 2014, well before he granted an interview to The Toronto Star
using the name Harun Abdurahman, Cabana said. In the interview, he justified the 2014 attacks on Parliament Hill in Ottawa that left an unarmed soldier dead, and he expressed support for ISIS.
He was in contact with alleged terrorists in the months following, but police "were never able to establish the nature of the communications" because they were encrypted, the deputy commissioner said.
Police arrested Driver in June 2015 and charged him with knowingly participating in the activities of a terrorist group and a search of his computer yielded a recipe for explosives, Cabana said.
A court granted him a peace bond, requiring he maintain good behavior for a certain period, and ordered him to be electronically monitored.
He moved from Winnipeg to his sister's home in Strathroy in July 2015, Cabana said.
When the RCMP recently received information from the FBI, including "a video of a man in the final stages of an explosives attack," they reached out to law enforcement partners across the country and identified the man in the video as Driver.
In the video, a man in a black balaclava appears to be reading something to the side of the camera. He invokes "the bodies of filthy French lying in the street" and says Canada has received many warnings to stay off Muslim lands and discontinue its participation in the fight against ISIS.
"You still have a heavy debt that has to be paid," he says.
Leonard Tailleur, who represented Driver in the previous case on which he was granted the peace bond, said he hadn't spoken to Driver since February, nor has he spoken to police.
He said he was shocked to learn of his former client's death.
"He was going to get married to a gal in Toronto," the attorney said.
Regarding the previous case, he said police had intended to charge Driver with terrorism threats based on his social media postings, but Driver and police reached a peace bond settlement allowing the RCMP to monitor Driver for up to a year.
"He was allowed to live where he wanted to as long as he told the RCMP. He had a phone that they gave him, that they were able to monitor," Tailleur said.
The last Tailleur heard, he said, Driver was supposed to keep the phone until the end of August and the RCMP would continue to monitor him through December.