The vehicle crashed through a wall and into the bedroom of a property on Russell Street in Mount Evelyn about 11.15am.
Resident Linda Cooke was folding washing in her room only 15 seconds before the truck crashed through her wall.
9News understands the truck driver was at a property across the road unloading skip bins when his truck started rolling back.
Cooke’s son, Cameron, said he was in “disbelief”.
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“I just got a phone call from Mum. She was distressed, she couldn’t make heads or tails of it,” he told 9News.
“She said a truck came in through her bedroom. It’s pretty scary.”
The local council building surveyor has been called to the scene to assess the site, while investigations into the incident continue.