OTTAWA, Ontario (AP) — The mother of the gunman who carried out the deadly attack on Canada's seat of government said Thursday that she is crying for the victims of the shooting rampage, not her son.

In a brief and tear-filled telephone interview with The Associated Press, Susan Bibeau said she did not know what to say to those hurt in what authorities are calling a terrorist attack by a recent convert to Islam.

"Can you ever explain something like this?" she said. "We are sorry."

In a separate email to the AP expressing horror and sadness at what happened, Bideau said that her son seemed lost and "did not fit in," and that she hadn't seen him for more than five years before they spoke over lunch last week. "So I have very little insight to offer," she said.

Investigators similarly offered little information about the gunman, 32-year-old petty criminal Michael Zehaf-Bibeau.

Authorities said he killed a soldier standing guard at Canada's tomb of the unknown Wednesday, then stormed the nearby Parliament building, where he was shot to death.

It was Canada's second deadly attack in three days by a recent convert to Islam, and raised fears that the country is suffering reprisals for joining the U.S.-led air campaign against Islamic extremists in Iraq and Syria.

Prime Minister Stephen Harper linked both episodes to the "savagery" of radical ideologies abroad.

After initially reporting that two or three assailants may have taken part in the shooting rampage, Canadian police conceded Thursday that Zehaf-Bibeau was the lone gunman.

His mother, who has homes in Montreal and Ottawa, said she was devastated for the victims of the attack.

"If I'm crying, it's for the people," she said, struggling to hold back tears. "Not for my son."

Government officials credited 58-year-old Parliament sergeant-at-arms Kevin Vickers with shooting the attacker just outside the MPs' caucus rooms.

Vickers, a former Royal Canadian Mounted Police officer, serves a largely ceremonial role at the House of Commons, carrying a mace and wearing rich green robes, white gloves and a tall imperial hat.

Members of Parliament gave him a rousing standing ovation Thursday morning for saving their lives. As Vickers walked into the House of Commons, his lips quivered in emotion, and he acknowledged the applause by nodding solemnly.

Vickers said in a statement that he was "very touched" by the attention but that he has the close support of a remarkable security team.

In an uncharacteristically personal speech, Harper urged members of Parliament to seek medical help if they are suffering stress from the attack.

"Here we are in our seats, in our chamber in the very heart of our democracy, at work" Harper said. "We will not be intimidated."

Harper noted that both of this week's terror attacks in Canada came from citizens born in Canada.

On Monday, a man Harper described as an "ISIL-inspired terrorist" ran over two soldiers in a parking lot in Quebec, killing one and injuring the other before being shot to death by police.

Court records that appear to be Zehaf-Bibeau's show that he had a long rap sheet, with a string of convictions for assault, robbery, drug and weapons offenses, and other crimes.

Elizabeth May, the leader of the Green party, said in Parliament that the attacks were probably "the acts of isolated, disturbed and deeply troubled men who were drawn to something crazy."

"I do not believe that it was a vast network, or that the country is more at risk today than it was last week," May said.

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Satter reported from London. Gillies contributed from Toronto.