A "major incident" has been declared, and there have been a "number of fatalities", the London Fire Commissioner has confirmed. Dany Cotton was unable to say how many had died due to the scale of the "unprecedented" fire.
The London Fire Brigade was first called at shortly before 1am on Wednesday to the Grenfell Tower in Latimer Road, North Kensington, London.
Over 50 people have been taken to hospitals, London Ambulance Servicesaid.
Efforts to evacuate residents continued for hours after the fire first broke out, the Metropolitan Police confirmed, and as of 6 am the fire continued to rage.
Forty fire engines and 200 firefighters responded, according to London Fire officials. The first emergency responder was on the scene six minutes after the first call was received.
The building, constructed in 1974, is 24 stories tall and contains 120 homes, according to the Royal Borough of Kensington and Chelsea.
Residents' groups had issued numerous warnings in the past few years about the block's fire safety provisions.Read more here.
An emergency number Casualty Bureau has been set up on 0800 0961 233.