A Saskatoon resident suffered burns on their hands when they tried to move a cardboard box, filled with burning tax papers, before the fire grew out of control.
The flames also caused $150,000 in damages to the home in the College Park East neighbourhood.
Saskatoon Fire Department (SFD) crews were called to a house in the 700 block of Trent Crescent on Sunday night shortly before 9 p.m.
They scrambled five fire engines and those first on the scene found light smoke emanating from the structure.
Everyone inside had already evacuated.
The investigation concluded the residents deliberately started the fire inside the house, intending to burn garbage inside a cardboard box.
SFD Assistant Chief Wayne Rodger told Global News the residents were burning old tax papers.
He said they started the fire in the house and made it as far as the patio door before having to drop the box.
He told Global News he presumed they “weren’t able to appreciate how fast a fire will grow,” clarifying that flames spread “exponentially.”
He called the decision a misjudgment and recommended people recycle unwanted paper or use shredders for confidential documents.
He said any further investigation into what the residents were destroying is a matter for the insurance company.
He also said he didn’t know the severity of the burns suffered by the resident but said Medavie Health Services West paramedics treated them right away.