Hundreds of firefighters battled through the night after flames engulfed a 24-storey apartment tower in West London early Wednesday.
More than a 30 people have already been treated for smoke inhalation and other injuries according to authorities.
It is feared that others may be trapped inside the burning building.
The fire is believed to have started around 1 a.m. in the Grenfell Towers in North Kensington near Notting Hill.
More than 200 firefighters and 40 fire trucks remain on scene.
More than 20 ambulances have also been dispatched.
“Firefighters wearing breathing apparatus are working extremely hard in very difficult conditions to tackle this fire,” said London Fire Brigade Assistant Commissioner Dan Daly.
Homes on surrounding blocks are also being evacuated and the nearby A4 motorway is shut in both directions.
The cause of the fire remains unknown.
The structure was built in 1974 and houses 120 apartments.
It underwent an estimated $17 million in refurbishment in 2016 and is managed by Kensington and Chelsea Tenant Management Organisation on behalf of the council.