Twelve people have been confirmed dead following a fire which ripped through a 24-storey housing block in west London in the early hours of Wednesday morning.
Flames raced through the high-rise Grenfell Tower block of flats in the north Kensington area after taking hold before 1am. Witnesses reported many residents desperately calling for help from windows of upper floors.
Police said they are expecting the death toll to rise further, as there were up to 600 people thought to have been inside the tower of 130 flats at the time of the blaze.
Eighteen people are reportedly receiving critical care after 74 people were taken to hospital.
More than 200 firefighters, backed up by 40 fire engines, fought for hours to try to bring the blaze, one of the biggest seen in central London in recent years, under control.
The cause of the fire was not immediately known.
The block had recently undergone an STG8.7 million ($A14.6 million) refurbishment of the exterior, which included new external cladding, replacement windows and curtain wall facades.
Plumes of black smoke billowed high into the air over London for hours after the blaze broke out. Residents rushed to escape through smoke-filled corridors after being woken up by the smell of burning.
London Fire Brigade said the fire engulfed all floors from the second to the top of the 24-storey block. There were reports that some residents threw themselves out of windows to escape the flames.
“In my 29 years of being a fire fighter, I have never ever seen anything of this scale,” London Fire Brigade Commissioner Dany Cotton told reporters.
More than 10 hours after the fire broke out London fire brigade said it was still working to bring the fire under control, though the building was not in danger of collapse.