About 25 firefighters tackled a fire at a shop being used as a "suspected cannabis factory" in Finsbury Park on Monday (July 25).
The London Fire Brigade (LFB) was called to the shop with flats above in Fonthill Road just after 8pm.
Crews using four engines had the blaze under control by 9.15pm.
An extractor vent at roof level was destroyed by fire and part of a three-roomed flat on the third floor was also damaged.
The cause of the fire is under investigation by the LFB and the Met Police.
There were no reports of injuries.
A spokesperson for the LFB said cannabis factory fires can be particularly dangerous 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," they said.
"Firefighters can also be exposed to risks when dealing with the fires because of bad wiring and 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."
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