Eight fire engines and around 60 firefighters tackled a fire at a shop with flats above on Willesden High Road.
Most of the ground floor and part of the void between the ground and first floor were damaged by fire. Firefighters rescued two people from the third floor using a short extension ladder. Three further people left the property before the Brigade arrived. They were all taken to hospital by London Ambulance Service crews.
The Brigade's 32-metre turntable ladder was used as an observation platform.
Station Commander Chucks Abili, who was at the scene, said: "Crews worked hard to access the voids and bring the fire under control.
"The fire was producing heavy smoke, so we advised local residents keep their windows and doors closed.
"Willesden High Road was closed between Bertie Road and Hawthorn Road and we encouraged people to avoid the area."
The Brigade's Control Officers took the first of eight calls to the fire at 1308 and mobilised crews from West Hampstead, Park Royal, North Kensington, Kentish Town and Wembley fire stations to the scene. The fire was under control by 1521.
The fire is believed to have been caused by an electrical fault in the lighting.