Witnesses have described screams of terror and people jumping from their flats as fire ripped through Grenfell Tower in west London.
One described hearing a neighbour screaming for help before apparently jumping out as flames engulfed his seventh-storey flat.
Speaking from an evacuation centre on Freston Road, the woman, who asked not to be named, said: "There was a woman stood behind me who was shouting to someone she knew on the seventh floor.
"She was on the phone trying to speak to him, she was obviously very emotional because the flats were blazing at this point. He looked like he was screaming to her.
"Police said for anyone at the windows to wave a rag or something so the firemen could rescue them, but we thought, 'How are they gonna do that?'
"I saw the woman later and she was hysterical. She said her friend jumped. The whole of his window was on fire."
One report quoted a witness as claiming they saw a woman throw her baby from the ninth or 10th floor of the block before she disappeared from sight. The baby was caught by a man below, according to the Huffington Post.
A number of people have died in the blaze, London Fire Brigade confirmed, but the exact figure is not yet known.
More than 50 people are being treated in hospitals across London.
Another witness, Samira, told BBC News: "I think the speed of the fire was the most shocking thing for everyone, how quick it literally went from zero to 100."
She claimed she had seen "a lot of people jumping out that basically didn't make it".
Another resident, called Zara, said she saw a woman throw her son, who was about five years old, from a fifth or sixth floor window to escape the blaze.
She told LBC: "One woman actually threw her son out of the window. I think he's OK. I think he might have just had some broken bones and bruises.
"I left my phone at home so I went back to grab it and, by the time I got back, the road was completely blocked off, the fire had dramatically spread.
"It was like a scene from a Hollywood movie."
Additional reporting by agencies