Terrible news out of China ... where 21 elite athletes died during a 62-mile ultra-marathon race when the group got caught in a freezing storm that appeared out of nowhere.
The event -- known as the Huanghe Shilin Mountain Marathon -- began Saturday morning when the weather was sunny and nice.
Most of the 172 runners had anticipated normal weather conditions and showed up to the race in shorts and t-shirts, typical running garb.
But things took a sudden turn just after noon around the Yellow River Stone Forest -- when a freezing cold storm moved in, punishing the runners with a barrage of hail stones, rain and icy winds.