An Alaska father was watching his son drive around on a snowmobile when it happened, officials said: The boy was there, and then he wasn't.
Sjohn Brown, 9, of Fairbanks, disappeared Saturday afternoon and was presumed dead when he and his snowmobile fell into a crevasse some 200 feet deep.
Officials said the accident happened about five miles northwest of the state's annual Arctic Man skiing and snowmobile event at Summit Lake.
After the father saw Sjohn's snowmobile drive behind a small mound and not reappear, officials said, he went to investigate. He found that his son's snowmobile had essentially fallen into an icy elevator shaft -- a moulin, a kind of vertical tunnel through which water enters a glacier.