Canadian Prime Minister Justin Trudeau said Saturday that his government’s focus is accountability and justice for the victims of the Ukrainian airliner that Iran says it shot down accidentally.

“We will continue working with our partners around the world to ensure a complete and thorough investigation, and the Canadian government expects full cooperation from Iranian authorities,“ Trudeau said in the statement tweeted by communications director Cameron Ahmad.

Iran said Saturday that it mistook the Ukraine International Airlines jetliner for a threat during hostilities with the U.S. The army said that the flight was flying near a sensitive Islamic Revolutionary Guard Corps military site when it was shot down due to “human error.”

Canada’s Foreign Affairs Minister Francois-Philippe Champagne said that at least 57 Canadians died in the crash.

“This is a national tragedy, and all Canadians are mourning together,” Trudeau said.