OTTAWA - Ottawa police are now saying they believe only one gunman was involved in Wednesday's shootings at the National War Memorial and on Parliament Hill.

Const. Marc Soucy says no other assailants are currently being sought and the investigation is ongoing.

Cpl. Nathan Cirillo, a reservist from Hamilton, was killed after being shot on the steps of the memorial while serving as an honour guard. The gunman then raced over to Parliament Hill, where he was killed in a gunfight in the halls of Centre Block.

Michael Zehaf Bibeau, born in 1982 and known to police in Montreal and Vancouver, has been identified as the shooter.

Zehaf Bebeau was killed just metres away from where hundreds of MPs were meeting for their weekly caucus meetings.

Wednesday's events placed much of the national capital under lockdown as police scoured the city's downtown core for other possible assailants.

The mother of the man accused of killing a soldier at the National War Memorial before opening fire in Parliament says she's devastated for the victims of the attack.

In a brief and tear-filled telephone call with the Associated Press, Susan Bibeau said she was crying for the victims, not her son.

She also called the attack inexplicable and said "We are sorry."

In an earlier email exchange, Bibeau said she was mad at her son and that part of her "wants to hate him at this time."

She said he seemed lost "and did not fit in" but added she had little insight to offer because she hadn't seen him in five years until she spoke with him last week over lunch.

With files from The Associated Press.