Prime Minister Stephen Harper has said "Canada will not be intimidated" and will fight terrorism, after a Canadian soldier was shot dead by a gunman near the parliament in Ottawa on October 22.
The suspected killer was shot dead following a heavy exchange of gunfire with police inside the parliament building.
Harper addressed the nation amid a massive security operation which saw parts of the capital locked down as security forces searched for other potential suspects.
The incident came after Canada on October 21 raised its terror threat level, following the death of another soldier in a hit-and-run attack by a Muslim convert on October 20.
In his address, Harper called both incidents "terrorist attacks."
He said the attacks would strengthen Canada's determination in the fight against terrorism alongside its allies.
"They will have no safe haven," Harper said.
The dead soldier was identified as Corporal Nathan Cirillo, who was on guard duty at a war memorial near the parliament when he was killed.
Meanwhile, media reports said Canadian police were investigating a man named as Michael Zehaf-Bibeau as a possible suspect in the shootings.
Canada's "Globe and Mail" newspaper reported, citing federal authorities, that the Canadian-born Zehaf-Bibeau, who is in his early 30s, was known to Canadian authorities.
The paper said that Zehaf-Bibeau was recently designated a "high-risk traveler" by the Canadian government and that his passport had been confiscated.
U.S. President Barack Obama condemned the Ottawa shootings as "outrageous attacks" and reinforced the need for vigilance.
Obama, who spoke by telephone with Harper, said the motive for the shootings remained unknown. Obama said he offered condolences on behalf of the American people.
Canada earlier this month joined the U.S.-led coalition conducting air strikes against Islamic State (IS) militants in Iraq and Syria.
However, authorities had said on October 21 that the decision to raise the terror threat level was prompted by a rise in "general chatter" from radical groups such as IS and Al-Qaeda but said there had not been a specific threat.
No group, Islamic or otherwise, claimed responsibility for either the attack in Ottawa or the one near Montreal on October 20.
The perpetrator of that attack, 25-year-old Martin Rouleau, who converted to Islam last year, was among 90 people being tracked by police on suspicion of taking part in militant activities abroad or of planning to do so.
Like Zehaf-Bibeau, Rouleau also had his passport confiscated earlier this year and was prevented from traveling to Turkey.
With reporting by Reuters, AP, AFP, dpa, and BBC