Ukraine has declared a national day of mourning after a Ukrainian commercial jet crashed in Iran, killing all 176 passengers and crew on board.

The Boeing 737 went down shortly after takeoff from Tehran, just hours after Iran fired missiles at American forces in Iraq.

Canada's Prime Minister Justin Trudeau says his country will be part of the investigation. Sixty-three of those killed were Canadian citizens.

Al Jazeera's Laura Burdon-Manley reports.