WATCH: More footage from the China-Nepal border shows a massive wall of debris surging down a Himalayan valley, engulfin

WATCH: More footage from the China-Nepal border shows a massive wall of debris surging down a Himalayan valley, engulfing roads, power lines, and buildings in seconds. Investigators suspect a magnitude-4.4 earthquake triggered an avalanche that temporarily dammed a river before bursting, releasing the debris-laden flood.