A vast, intense wildfire that has forced more than 88,000 people to flee the Canadian oil city of Fort McMurray was spreading overnight, threatening the local airport and engulfing more communities, authorities said.
More than 1,600 homes and buildings have already been destroyed by the "heartbreaking" blaze, which has turned skies blood-red and rained ash on residents fleeing on crowded highways.
More than 18,500 acres have already been scorched.
