A makeshift cannabis "factory" was discovered by firefighters after white smoke was spotted billowing from the roof of a semi-detached house.
West Midlands Police said overloaded wiring at the property in Hamstead Hall Avenue in Handsworth Wood, Birmingham, posed a "huge threat" to public safety and had endangered the lives of neighbours.
Crews from Handsworth community fire station attended the blaze at about 6.50am on Sunday.
Pictures posted on the station's Twitter account showed a jumble of wires rigged up to a fuse box inside the three-bedroom home.
In a comment on the same Twitter page, the West Midlands Police Cannabis Disposal Team said: "Huge threat to public safety. Neighbours at risk of damage or death!"