More than 200 firefighters are tackling a massive blaze at a block of flats in London, with reports of people trapped in their homes.
Forty engines were called to the 27-storey Grenfell Tower at just after 1.15am on Wednesday, on the Lancaster West Estate, north Kensington.
Police said a "number of people are being treated for a range of injuries", including two for smoke inhalation, as pictures from the scene showed flames engulfing most of the block.
Actor and writer Tim Downie, who lives around 600 metres from the scene in Latimer Road, told the Press Association he feared the block could collapse.
He said: "It's horrendous. The whole building is engulfed in flames. It's gone. It's just a matter of time before this building collapses.
"It's the most terrifying thing I've ever seen. I just hope they have got everyone out.
"The first I knew was the noise of sirens, helicopters and shouting. I saw it engulfed in flames.
"People have been bringing water, clothes, anything they've got to help, out to the cordon.
"I have seen people coming out in their bedclothes - it's just very distressing."
Residents are continuing to be evacuated from the tower block, the Metropolitan Police said.
Meanwhile, people are reporting hearing "bangs" from the scene hours after the fire first started, just before 1am.
Fire crews from north Kensington, Kensington, Hammersmith and Paddington and surrounding stations were at the scene with the fire burning from the second to the top floor.
The cause of the fire is not known at this stage, London Fire Brigade said.
Fabio Bebber wrote on Twitter: "More screams for help as the fire spreads to another side of the building.
"We can see how quick the fire spreads via the external panels. It's unbearable hearing someone screaming for their lives at #grenfelltower."
George Clarke, who presents the Channel 4 TV show Amazing Spaces, told Radio 5 Live: "I was in bed and heard 'beep, beep, beep' and thought, 'I'll get up and run downstairs as quickly as I could'.
"I thought it might be a car alarm outside and saw the glow through the windows.
"I'm getting covered in ash, that's how bad it is. I'm 100 metres away and I'm absolutely covered in ash.
"It's so heartbreaking, I've seen someone flashing their torches at the top level and they obviously can't get out.
"The guys are doing an incredible job to try and get people out that building, but it's truly awful."
Celeste Thomas, who lives near the scene, said: "Police moving everyone back. I literally live across the road. Hundreds of people outside. Residents and families trying to find each other.
"Police have moved everyone back out of direct sight but can hear cracking and debris falling."
London Fire Brigade assistant commissioner Dan Daly said: "Firefighters wearing breathing apparatus are working extremely hard in very difficult conditions to tackle this fire.
"This is a large and very serious incident and we have deployed numerous resources and specialist appliances."
London Ambulance said it had sent a "number of resources" to the scene, including its Hazardous Area Response Team.
London mayor Sadiq Khan tweeted: "Major incident declared at Grenfell Tower in Kensington" and urged people to follow London Fire Brigade on Twitter.