Fire investigators now know what caused a house explosion in St. Joseph County, Michigan.
It happened just before nine Tuesday morning near White Pigeon, Michigan on U.S. 12.
Firefighters say by the time they arrived the house was demolished after something exploded inside the home. By the time help arrived, the man inside was waiting outside and walking around. Firefighters say he was conscious and suffering from burns.
Authorities have identified the man injured in the blast as David Stanley.
Officials say the gas that caused the explosion came from a propane tank that was in Stanley’s house. The tank was being used to run a portable heater.
"The homeowner himself was in the basement, when he lit a cigarette which set off the explosion," investigators say. "The homeowner was there by himself, he actually had to climb out of the basement after the explosion."
Stanley was flown to a burn unit in Kalamazoo. Authorities say he is in stable condition.
But officials say the investigation into the fire is not over, and are hesitant to rule out foul play.