London Fire Commissioner, Dany Cotton said there were still "unknown numbers" of people in the smoldering ruins of Grenfell Tower, in north Kensington.
People have been desperately seeking news of missing family and friends, after 12 people were confirmed dead. Police have warned that the number of deaths is expected to rise.
Thirty-four people remain in hospital - 18 of whom are in a critical condition.
Prime Minister Theresa May, who is visiting the scene, has promised a full investigation, as questions are asked about the speed at which the fire spread.