"Sadly I can confirm that there are now 12 people who have died, that we know of", Police Commander Stuart Cundy said. At least 30 people have been taken to hospitals.
Witnesses described a white, polystyrene-type material falling like snow from the building as it burned.
Firefighters gather at the building before searching for people who may have been trapped inside. Michael Paramasivan, who lives on the seventh floor with his girlfriend and young daughter, said he ignored official advice to stay in your home.
He said he saw people waving flashlights from the top levels of the building and saw rescuers "doing an incredible job" trying to get people out.
Amess said that the material used in cladding is "something else which must be acted on immediately" and looked at as we can not risk any more people's lives.
Labour MP Jim Fitzpatrick - chairman of the all-party Parliamentary Fire Safety and Rescue Group - said the Government has resisted calls to install sprinkler systems in high-rise blocks in the wake of the Lakanal House tragedy. It was fire up, up, up.
"There are already disturbing reports emerging of the pipework in the building for a fire emergency being out of action", Ritson says.
A witness, Safyha, told BBC the fire had spread from one side of the building to engulf the entire tower.
After the fire today, the group said: "All our warnings fell on deaf ears and we predicted that a catastrophe like this was inevitable and just a matter of time".
Edward Daffarn, 55, is one of the campaigners from Grenfell Action Group, which published a series of blog posts warning of fire safety concerns with Kensington and Chelsea Tenant Management Organisation (KCTMO), the private business that has the contract with the local authority to run its social housing.
"I'm lucky to be alive".
"They didn't listen, we even went to the MP, Victoria Borwick, we had quite a few meetings - this is what happens".
"This is mass murder and these people need to be put into court", he said.
It is understood Grenfell Tower was crammed with families and it is feared children will be among the dead.
The group said there was only one entry and exit to the tower during improvement works at the block in Latimer Road and it had issues with evacuation procedures.
In a blog on November 20, the activist group predicted that only "a catastrophic event" leading to "serious loss of life" would bring the outside scrutiny needed to make conditions safe for residents.
Many were awake at the time the fire broke out having their early morning meal before beginning the daily fast for the holy month of Ramzan.
Jody Martin said he got to the scene just as the first fire engine was arriving.
Construction firm Rydon, which carried out the refurbishment of the tower, said in a statement that its work "met all required building control, fire regulation, and health and safety standards". London Mayor Khan declared the fire as a "major incident" and said questions will need to be answered over the safety of such tower blocks.
The fire has been burning for more than three hours and stretches from the second to the 24th floor of the building.