Several media reports have identified the soldier as 24-year-old Cpl. Nathan Cirillo, a reservist who served with the Argyll and Sutherland Highlanders of Canada.
His friend Marie Michele told CBC News he had a young son.
"Nathan was a good man. He would give anything to anyone," she said. He was also a former Goodlife Fitness employee and joined cadets at age 13.
Cirillo also maintained an active Instagram account, posting photos of his dog and himself in uniform.
The Hamilton Spectator reported that members of the regiment were on tour guarding the memorial in the days leading up to the shooting.
Witnesses described seeing a soldier, who was serving as a ceremonial guard at the foot of the cenotaph, shot at point-blank range before the gunman ran off in the direction of Parliament Hill.
The shooting triggered a day-long siege and manhunt in the national capital, with reports of multiple gunmen.
Parliament Hill remains under lockdown while the search for other gunmen continues in the downtown core.
The incident comes just two days after two Canadian soldiers were run over — and one of them killed — in Quebec by a man with jihadist sympathies.
With files from the Canadian Press
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