Around 200 firefighters and around 40 fire engines remain at the scene this afternoon, with the blaze still smouldering and many tenants unaccounted for.
But this fire appeared to be tear up the building from the outside, gutting the outer apartments and blackening most of the facade.
"Local residents said they had warned local authorities about fire issues in the building, a public housing block built in 1974 and containing 120 homes, according to the Royal Borough of Kensington and Chelsea".
Cladding had been added to the outside of the building, blamed by some residents for helping the fire to spread so quickly.
Fire Commissioner Dany Cotton said hundreds of firefighters expected to be on the scene for at least another 24 hours and she would not speculate about the cause of the blaze at this stage.
Cotton told reporters she'd never seen anything like the fire in her almost 30 years as a firefighter.
The Metropolitan Police confirmed in a statement that a number of people have been killed in the fire.
Witnesses described people leaping from the building and of trapped children banging on windows as the fire broke out at around 1 a.m. local time.
"We saw the people screaming", she said.
'Somebody did, a gentleman ran forward and managed to grab the baby'. "There's a man who threw two of his children", he told the BBC, beginning to tear up. Tiago Etienne, 17, said he saw about three children between the ages of 4 and 8 being dropped from around the 15th floor.
"Firefighters wearing breathing apparatus are working extremely hard in very difficult conditions to tackle this fire", he said in a post on the brigade's Facebook page.
Death toll rises to 12 in London apartment building inferno
They said an evacuation of the block was "underway" and at least two people were being treated at the scene for smoke inhalation. In this image made from video provided by Celeste Thomas @MAMAPIE, a building is on fire in London , Wednesday, June 14, 2017 .
Sikh resident Harjinder Kukreja wrote on Twitter, "Sikh Gurudwaras in London have started collecting and distributing spare clothes, toys, toiletries for Grenfell Tower evacuees".
Other residents told harrowing tales of their own escapes and frustration at not being able to help neighbours. She and her grandson sat outside the building, helplessly watching those trapped on higher floors.
He declined to give any details of the number of people who may be missing.
Michael Paramasivan, who lives on the seventh floor with his girlfriend and young daughter, said he ignored official advice to stay in your home. We don't really see fires like this anymore.
"There was smoke everywhere, people screaming and shouting ..." When she got downstairs, there was only four of them with her. It was fire up, up, up.
The major fire comes just 10 days after a terrorist attack occured in the city. "Help! Help!' and putting their hands on the window and asking to help them", Amina Sharif, a witness, told Reuters.
"I'm lucky to be alive".
"I was yelling at everyone to get down and they were saying, 'We can't leave our apartments, the smoke is too bad on the corridors'". "I consider this mass murder", he said of the blaze. The group has raised concerns about testing and maintenance of firefighting equipment and blocked emergency access to the site. In a blog from November previous year, the Action group warned that "only a catastrophic event will expose the ineptitude and incompetence of our landlord, the Kensington and Chelsea Tenant Management Association, and bring an end to the unsafe living conditions and neglect of health and safety legislation that they inflict upon their tenants and leaseholders".
"You just don't know, right now we can only offer prayers", he said.
"He called us this morning to say the flats were on fire and he couldn't breathe".
London's mayor Khan said questions needed to be answered over the safety of tower blocks after some residents said they had been advised they should stay in their flats in the event of a fire.