Canadian Prime Minister Mark Carney delivered a sombre national address after a deadly fire at CFB Wainwright in Alberta killed four service members and left dozens more seriously wounded.Carney called it one of the worst peacetime tragedies to strike the Canadian Armed Forces on home soil, ordered flags at federal buildings lowered to half-mast and said the country was mourning those who lost their lives.He praised military and civilian crews who fought the blaze through the night and vowed that Canada would stand by the injured, the families of those killed and the wider armed forces community.