Canada's prime minister has condemned the "brutal and violent" shooting of a Canadian soldier in Ottawa and a hit-and-run that killed another soldier earlier this week, saying the incidents are grim reminders that Canada is not immune to terrorism.

"But let there be no misunderstanding, we will not be intimidated," Stephen Harper said in a televised address to the nation late on Wednesday.

Harper said the attacks would not deter Canada from working with international allies to fight terrorism around the world, and vowed to go after those who are involved.

"This will lead us to strengthen our resolve and redouble our efforts, to fight against the terrorist organisations who brutalise those in other countries with the hope of bringing their savagery to our shores," he said.

Harper spoke hours after a gunman shot and killed a soldier guarding a war memorial then stormed the Canadian parliament before he was killed.

The prime minister was holding a meeting with party members in the parliament building as the gunfire erupted. Members of the parliament were also inside the building when the attack took place.  

Canadian authorities and the media have identified the suspected attacker as Michael Zehaf-Bibeau.

The 32-year-old suspect was deemed a "high-risk traveller" by intelligence services, and according to media reports he recently had his passport confiscated.

'Threat level up'

No information has as yet been given as to a possible motive for the attack, which began shortly before 10am local time (14:00 GMT).

"A guy came from the side, my left hand side and came over with the rifle and shot at the man, then the guy went falling down and everybody was just in shock, couldn't believe that something like this could just happen or be real. It was just beyond realism," one witness told Al Jazeera.

The dead soldier was named in reports as Corporal Nathan Cirillo, part of a detachment on ceremonial duties at Parliament Hill, the heart of Canada's national government and home to its legislature.

At least three people were admitted to hospital with minor injuries.

The attack came hours after Canada raised its terrorism threat level from low to medium, the highest it has been for four years.

It also comes two days after two Canadian soldiers were run over, and one of them killed, in Quebec.

Marc-Andre Viau, a witness to Wednesday's shooting, told the AFP news agency that he saw a man run into a meeting inside parliament, chased by police who yelled "take cover". That was followed by up to 20 gunshots.

People fled parliament by scrambling down scaffolding being used in renovations, witnesses told the Canadian Press news agency.

Police had by this point sealed the area and were combing buildings for more gunmen, with unconfirmed reports they were positioned on roofs. Police said the investigation was active but no one else had been found.

Speaking to Al Jazeera from parliament , Senator Jim Munson said "people are quite shaken. This kind of terrorist attack did not seem possible."