The wall of snow rushed down Mount Jumbo shortly after 4 p.m., destroying the two-story house where neighbors said retired University of Montana Professor Fred Allendor lived with his wife, the Missoulian reported.
City police said emergency crews found the unidentified child, who apparently had been playing in the back yard of another house when the avalanche hit, in the snow about an hour later, the newspaper said.
An hour after that Allendorf was found alert and responsive beneath his home's chimney, the Missoulian said. The search went on for his wife, whose name wasn't available.
A second house was damaged by the snow slide.