TOXIC smoke forced the evacuation of dozens of Dennison Ave residents for five hours last Saturday night.
Hoppers Crossing CFA firefighter Erol Ibrahim said the smoke had come from a back room of a house containing chemicals.
The sole occupant of the house, a male, had fled after telling firefighters the smoke was coming from a wallpaper-removing machine, he said.
“He met us at the front of the house and told us not to worry, he was having trouble with the machine.”
But a thermal imaging camera and firefighters in breathing apparatus determined the source of the smoke was from the chemicals.
The police major drug squad is now investigating.