MPs barricaded themselves into a parliamentary caucus room by piling furniture against the doors, while others fled the building by clambering down scaffolding erected for repair work.
Media reports described the scenes as unlike anything Canada has witnessed in modern history.
In a touch of fate, the Government and Opposition were in adjacent rooms, both holding separate discussions on efforts to crack down on homegrown terrorism.
Prime Minister Stephen Harper, an outspoken critic of the Islamic State movement and other militant groups, has been considering the introduction of new antiterrorism legislation and has actively supported the American-led military effort to degrade the IS expansion in Syria and Iraq.
The shootings came at a time when Canada was already feeling tense, two days after an incident in Quebec when Martin Couture-Rouleau drove at two soldiers in his car.
One soldier died and Coulture-Rouleau was later shot dead by police.
The Government had previously confiscated Coulture-Rouleau's passport when he attempted to fly to Turkey where he was suspected on trying to join Islamic extremists fighting in Syria.
Canada earlier this week raised its domestic terror threat level from low to medium because of what the public safety ministry described as an increase in general chatter from radical Islamist organisations.
The raising of the threat level followed a decision by the Canadian Government to take part in the allied air campaign against the IS extremist group in Iraq and deployed two warplanes and a refueller aircraft to fly sorties from Kuwait.
Canada already has a small number of special forces soldiers in Iraq.
All of this can seem a long way from New Zealand, but some serious warnings are contained in the Canadian incidents.
Like Canada, New Zealand is now seen as a close friend of the United States, Australia and Britain, the five countries involved in the Five Eyes spy network.
Prime Minister John Key last week lifted New Zealand's national threat level in response to risk posed by foreign fighters and IS from ''very low'' to ''low'', surprising many New Zealanders who were unaware this country even had a threat level.
Mr Key said the review of settings was in relation to foreign terrorist fighters.
Such fighters taking part in or returning from the conflict zone were a concern for many countries.
On Wednesday, a 17-year-old Australian was seen surrounded by IS terrorists, brandishing an automatic weapon, and repeating threats against the US, Britain and Australia.
An inquiry has been launched into how a schoolboy could tell his family he was going fishing and turn up in northern Syria several weeks later.
New Zealand has also had radicalised jihadists leaving to fight in Syria.
The lifting of the New Zealand threat level means where previously the threat of a terrorist attack was assessed as unlikely, it is now assessed as possible but not expected.
The New Zealand Prime Minister has been coy about New Zealand's involvement in Iraq, suggesting troops may go overseas to train Iraq military, rather than fight. But there are concerns New Zealand special forces are already overseas, either preparing to fight on the ground or already doing so.
Also of note is New Zealand's elevation to the United Nations Security Council for a two-year term.
This will be a challenging time for both the council and New Zealand.
Mr Key says New Zealand is determined to make a positive contribution and, in particular, to represent the perspective of small states.
The incidents in Canada, the migration of radicalised Muslims towards the Middle East conflict, and the rising threats of homegrown terrorism are of concern.
New Zealand is in a prime but dangerous position, and being at the bottom of the globe is no barrier to terrorism.
Mr Key needs to ensure all steps are made to protect New Zealanders, not by fobbing off their concerns, but by actively engaging citizens and sharing information.
