The survivors were an elderly couple and an 8-year-old boy, police Sgt. Travis Welsh said.
No one else had been reported missing.
All three were taken to a hospital. Their conditions weren't immediately known, but Welsh said the man was talking to rescuers.
"It's pretty incredible that we pulled three living bodies out of there," Welsh said.
Part of the house was upended and lying on its side, and the area around it appeared to be strewn with debris. A utility pole tilted at a pronounced angle.
The elderly couple lived in the house that was destroyed.
He was responsive and appeared to have no broken bones, according to a rescuer who said a fallen chimney had created an air pocket roughly 5 feet by 2 feet that saved the man from suffocation...
Night fell and portable floodlights were trucked in to illuminate the search site as a trained avalanche crew shoveled through the wreckage. Another hour passed and a woman [identified by neighbors as Allendorf's wife] was pulled from the ruins of the house. She lay in what a law enforcement officer on the scene said was a similar air hole. Incredibly, she too was breathing.
The boy had apparently been playing outside a home at the southeast corner of Van Buren and Holly when the slide struck. He was found buried under snow between the house and a high wooden fence roughly 10 feet away.
The avalanche slid down Mount Jumbo into the northeast Missoula neighborhood at about 4 p.m.
Authorities say avalanche conditions around the city remained dangerous Friday night after a storm brought blizzard conditions to much of the region.
Police asked residents of vulnerable neighborhoods to consider leaving but did not require or recommend evacuations, Welsh said.
Some 50 neighbors and first responders dug frantically through the snow and debris, the Missoulian reported.
Firefighters with avalanche probes — long poles used to penetrate the snow to find victims — then took over, and the boy was pulled from the snow at about 5:15 p.m.
A natural gas leak was also reported in the area, and utility crews were summoned.
Cheryl McMillan, who lives near the house that was destroyed, told the Missoulian she heard a roar, but didn't know what it was at first.
"Then, when we looked again, we saw that their whole house was kind of no longer there, at least the top floor," she said.
McMillan said she has lived in the neighborhood for 31 years and has never seen an avalanche before.