The unsafe disposal of smoking materials is believed to have caused a fire in a shed in Strimon Close, Edmonton.
Four fire engines and around 25 firefighters attended the incident.
Two sheds were destroyed and the rear of two nearby houses were damaged. Fortunately, there were no reports of any injuries.
A London Fire Brigade spokesperson said: "If you're a smoker it’s absolutely vital you ensure your cigarette is completely out when you’ve finished smoking it.
“If you don’t, you risk causing a fire which could not only destroy your home, but also cost you your life."
The Brigade was called at 0113 and the fire was under control by 0205.
Fire crews from Edmonton and Enfield fire stations attended the incident.