George Clarke, from Channel 4’s Amazing Spaces, has spoken of witnessing fire tear through Grenfell Tower in west London.
Several residents so far have been confirmed dead and more than 50 people are being treated in hospital, according to the London Ambulance Service.
George, who lives close to the tower, said he was “covered in ash”.
The 43-year-old posted 11 videos and photos of the burning tower block, describing it as “absolute hell”.
Talking to Radio 5 live he said: “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.”
Another eyewitness told the BBC that the building was “burned through to its very core”.
“It looks very bad, very very bad. I’ve never seen anything like this. It’s just such a big fire.
“The whole building is just crumbling. It’s just billowing black smoke.”
More than 600 residents tried to escape as the fire broke out in the middle of the night.
One neighbour saw people jumping from as high as 15 floors up to escape.
— George Clarke (@MrGeorgeClarke) June 14, 2017
Dany Cotton, Comissioner of the London Fire Brigade, said there had been “a number of fatalities” following a “unprecedented incident”.
She described the fire as the largest she had seen in her 29 years of service.