Four fire engines and around 25 firefighters attended a fire at a block of flats on Eton College Road in Chalk Farm.
Part of a fifth-floor flat was damaged by fire. There were no reports of any injuries.
The Brigade received the first of three calls at 1659 and Control Officers mobilised crews from Kentish Town, Soho and West Hampstead fire stations to the scene. The fire was extinguished by 1827.
The fire is believed to have been caused by refracted sunlight.
A London Fire Brigade spokesperson said: “Fires caused by refracted sunlight can happen all year round and are not as rare as you might think.
"Our advice is to make sure that you keep mirrors, crystals, glass ornaments and other reflective items out of direct sunlight at all times.”
The Brigade’s top three sunlight safety tips:
- Keep reflective items such as mirrors, crystals or glass objects away from sunny window sills and flammable materials.
- Make sure there are working smoke alarms fitted in every room where a fire can start except kitchens or bathrooms where heat alarms are more appropriate
- If you have a fire, close the door on the blaze, get out, stay out and call 999