A commemorative mass was held in Lac-Mégantic, Que., on Thursday to mark 10 years since the derailment tragedy in Lac-Mégantic, which killed 46 people. “Ten years ago, I was here at the commemorative mass, a few weeks after the terrible, terrible tragedy. It was a few months into my leadership of the Liberal Party of Canada and it was a moment where I understood the responsibility towards this community,” Trudeau said.