Around 125 firefighters have tackled a fire at a block of flats in Wembley.
London Fire Brigade said 20 fire engines were sent to the blaze on Elm Road on Monday evening.
The building and surrounding buildings were evacuated, the LFB said.
They said residents followed their evacuation procedure and were assisted by firefighters upon arrival.
The LFB added that residents also left the next door four storey block "as a precaution".
A spokesman said: "People are advised to avoid the area as crews respond.
"Nearby residents are being advised to keep their doors and windows shut to stay safe from any smoke in the area."
Two of the Brigade’s 32 metre turntable ladders were used as a water tower to help extinguish the fire, a spokesman said.
Firefighters were first alerted to the blaze at 4.42pm. In an update after 11pm, they said the fire had been brought under control.
Footage shared online showed smoke pouring from the building as firefighters tackled the blaze.
The cause of the fire is not yet known.
Firefighters from Wembley, Park Royal, Northolt and surrounding fire stations were send to the scene.
LFB said a section of the building's roof caught fire and asked members of the public to "please avoid the area as crews respond".