A Canadian soldier shot at the National War Memorial in Ottawa has died. Ottawa Police said the member of the Canadian Forces "succumbed to injuries" following a series of shooting incidents in the city this morning.
One male suspect has also died, police added, describing the incident as an "ongoing" operation with no-one currently in custody.
It was not clear how many people were behind the attack, with reports that one gunman had been shot dead by police. People inside the parliament building scrambled down scaffolding to escape, witnesses said, while other areas were in lockdown.
The shootings come two days after a recent convert to Islam killed one Canadian soldier and injured another in a hit-and-run incident before being gunned down by police. The soldier wounded in today's incident was taken away in an ambulance but his condition was not known.
Alain Merizier, a waiter in the parliament dining room, said he was on his way to work when he saw a gunman run from a car towards the parliament. "I saw a car suddenly stop," he told the BBC. "There was only one man in the car. He went out of the left side.
"He had a long gun and he ran away to the front and went inside the parliament. I heard one shot. I saw an officer running after him." Mr Merizier said the man had long dark hair and a small beard. He said: "I was astonished more than frightened. I said 'What happened?' You don't have time to be afraid, you are just surprised."
Vancouver South MP Wai Young said it had been "a difficult day". She said: "I am absolutely stunned because here in Canada we pride ourselves on being open, democratic and welcoming. To have this type of random terrorist attack happen in one of the safest places in Canada is quite shocking."
Royal Canadian Mounted Police asked people not to post videos or photos of the "ongoing incident" to ensure the safety of emergency services and the public. A photograph of chairs piled up against a door as a barricade was being heavily circulated on Twitter, apparently taken inside the meeting room in the parliament building where MPs earlier held their talks.
Mr Harper was due to meet Nobel Peace Prize winner Malala Yousafzai at an event in Toronto this evening but has cancelled following the shootings. Calum Jeffray, a research analyst at the Royal United Services Institute (RUSI), said the incident "mirrored" what happened in Quebec, where two soldiers were run over - one of them fatally - by a jihadi sympathiser.
Mr Jeffray told the BBC: "It does, if the reports are correct, seem to be some sort of co-ordinated attack. Again, the timing I think is significant - it has taken place just a few days after a separate incident in another part of the country. That is the bit that has suddenly taken a lot of people by surprise - we have seen multiple attacks within such a short timeframe."
The Princess Royal is due to visit Ottawa's National War Memorial next month. Anne is due to attend the monument's Remembrance Day service as part of a two-day tour of the area.
Ottawa mayor Jim Watson said he was "shocked and saddened" by today's events. "Ottawa police services are engaged with other law enforcement agencies at this time in pursuit of the criminal or criminals who have carried out this vicious and unwarranted attack," he said in a statement.
Ottawa Police chief Charles Bordeleau told a press conference that emergency services received a number of calls at 9.52am.
He confirmed the incident inside Parliament Hill occurred after the shooting of the soldier.
"All available resources have been deployed," he added. "Our priority is the safety and security of our community. This is an ongoing operation and we are asking members of the public to stay away from the downtown core."
He said police want to talk to witnesses of the shootings.
Mr Bordeleau would not confirm whether a second suspect was still at large. "We're in the process of clearing and security Parliament Hill," he said, adding that members of the public should remain "vigilant". Police added that the attack came as a "surprise", with the area currently considered a "medium" threat level.