Innocent people are killed by not so innocent people every day, and I agree that it's a tragedy this time and every time.
This is a tragic incident for sure, but not tragic enough to go to war over. The perpetrator, a mentally disturbed man with a criminal record, not a part of a terrorist conspiracy, is dead and so is an innocent man and there have been in the past and, unfortunately, will be more crazy people doing things just as bad and worse in the future.
Remember the École Polytechnique massacre? Remember the innocent Palestinian non-combatants killed by bombs in the not so distant past? Remember three mounted policemen who died unnecessarily in Moncton last June? What about the 22 year old man who was stabbed, beheaded and cannibalized while riding a Greyhound bus in Manitoba or the Chinese student who was dismembered and had his body parts mailed to different locations. All of these were every bit as tragic as the Ottawa incident, but none of them made us change our way of life, nor should this. It's not an Islamic conspiracy, it's a disturbed, mentally ill individual who may or may not have been influenced by Monday's assassination in Quebec.