Andrew Cohen is an author and journalist who writes a nationally syndicated column for the Ottawa Citizen. His latest book is "Two Days in June: John F. Kennedy and the 48 Hours that Made History" (Signal/Random House). He is a Global Fellow at the Woodrow Wilson International Center in Washington. The opinions expressed in this commentary are solely those of the author.

Ottawa (CNN) When terror came to the streets of Toronto this week -- in one of the worst mass killings in this country's history -- it challenged the sepia-soaked image of Canada as "a peaceable kingdom."

Andrew Cohen

Like other large, diverse democracies, Canada has learned that it is not immune to random atrocities. Four years ago, a gunman walked into Parliament in Ottawa, hunting politicians. He murdered a guard before he was killed.

What was striking in Monday's van attack, which killed 10 people and injured 14, was the public response: a mix of shock and incredulity tempered by reserve and order. Politicians of all stripes were calm. The media was careful. The police were disciplined. And the people were unfazed.

Instead of hysteria, accusation and anger, there were sorrow and sympathy. No xenophobic calls for vigilantism or limits on freedom. It was an extraordinary exercise in restraint -- a particularly Canadian response.

The misfit in a white rental van who sped down the crowded streets of north Toronto attacked the country's largest and most diverse city. Toronto -- more than half of whose 6.4 million residents were born abroad -- had never seen that kind of carnage.

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