Four fire engines and around 25 firefighters were called to a fire at a suspected cannabis factory in a house on Bertie Road in Willesden.
The stairwell from the ground to the first floor of a mid-terraced house was destroyed by fire and part of the first floor of the building was also damaged by the blaze. There were no reports of any injuries.
Sub Officer James Francis, who was at the scene, said: “On arrival, crews quickly made their way into the property and worked swiftly to bring the fire under control.
“Thankfully, no one was hurt and firefighters prevented the fire from spreading and causing further damage to the property.
“Cannabis factory fires can be dangerous because of the way criminals use unsafe wiring to illegally obtain electricity in order to grow the plants.
"Firefighters can also be exposed to risks when dealing with the fires because of bad wiring and booby traps at some of the properties.
"It's important that people know the key signs and inform the police so that they can act swiftly to prevent these dangerous fires from happening."
The Brigade was called at 0200 and the fire was under control by 0303. Fire crews from Willesden, Park Royal and West Hampstead fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.