London: At least six persons were killed and over 50 were in hospital after a huge fire raged overnight in a west London tower block, police said on Wednesday.

Up to 600 people were believed to be inside 120 flats in the 24-storey Grenfell Tower, in north Kensington, when the blaze began shortly after Tuesday midnight, The Telegraph reported.

London’s Metropolitan Police said the death toll was expected to rise. At least 50 injured people were taken to hospital — many were still missing after residents were left trapped on upper floors as flames spread rapidly up the building.

Eyewitnesses described people trapped in the burning tower screaming for help and yelling for their children to be saved, BBC reported. Some people threw their children from windows and others jumped from upper floors.

Some were reported to have attempted to use bin bags as makeshift parachutes. Firefighters rescued ‘large numbers’, but London Mayor Sadiq Khan said ‘a lot’ of people were unaccounted for.

London Fire Commissioner Dany Cotton said the cause of the fire was not yet known and it was too early to speculate on the building.

‘In my 29 years of being a firefighter, I have never ever seen anything of this scale,’ Cotton said.

Pictures from the scene showed flames engulfing the block and a plume of smoke visible across the capital, while others showed residents looking out of windows in the block.

Survivors were still reportedly being pulled from the block nine hours after the blaze started.

As an investigation into the cause of the fire began, residents reported that fire alarms had not sounded and that they were told to ‘stay put’ in their flats, The Telegraph reported.

The London Mayor said ‘questions need to be answered as soon as possible’.

Councillor Nick Paget-Brown, who represents the area in which Grenfell Tower is located, said the tower block contains some 120 individual apartments, many of which house young families, meaning the number of people trapped by the blaze could run into hundreds, Efe news reported.

More than 200 firefighters and 40 fire trucks were called to the block on the Lancaster West Estate, in north Kensington, at about 1.15 a.m. Police closed off roads nearby and asked people to avoid the area.

Scotland Yard said it was ‘likely to take some time before we are in a position to confirm the cause of the fire’.

Paul Munakr, who lives on the seventh floor, managed to escape. ‘As I was going down the stairs, there were firefighters, truly amazing firefighters that were actually going upstairs, to the fire, trying to get as many people out of the building as possible,’ he told the BBC.

A witness, Jody Martin, said: ‘I watched one person falling out, I watched another woman holding her baby out the window... hearing screams.’