Firefighters tackled a intense fire in a house which had been converted into a suspected cannabis factory on Dickens Avenue in Uxbridge.
The blaze badly damaged the detached house. The cause of the fire is believed to be electrical.
Station Commander Lucy Macleod-Cook said:
“When firefighters arrived they discovered a well developed fire on all floors of the two storey detached house. The crews quick action prevented the fire from spreading to neighbouring residents. There was no one in the property at the time of the fire and two neighbours left their home uninjured.
"Cannabis factory fires can be very severe because of the way criminals use unsafe wiring to illegally obtain electricity in order to grow the plants.
"They're often in top floors or lofts which means when a fire takes hold it spreads, destroying roofs and damaging neighbouring buildings.
"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 0550 and the fire was under control by 0737. Firefighters from Hillingdon, Hayes and Heathrow were at the scene.