Eight fire engines and around 60 firefighters tackled a flat fire on Northumberland Park in Tottenham.
Half of a five-roomed flat on the sixth floor of a residential block was alight. Two people left the affected flat before the Brigade arrived. Firefighters wearing breathing apparatus led a woman to safety via an internal staircase who was treated on scene for smoke inhalation.
Station Commander Chris Kendall, who was at the scene, said: "Firefighters worked hard in hot, challenging conditions to tackle a very intense fire.
"Due to heavy congestion, we urged people to avoid the area.
"The blaze was producing smoke and we advised those in the vicinity to close their windows and doors.
"One of the Brigade's 32-metre turntable ladders was used at the scene as an observation platform and as a water tower."
The Brigade was called at 1820 and the fire was under control by 2011. Fire crews from Tottenham, Edmonton, Holloway and surrounding fire stations attended the scene.
The fire is believed to have been accidental and caused by the unsafe use of incense sticks.