The man was a resident of Grenfell Tower, a 24-storey building that was completely engulfed in flames after a fire that began on a lower floor in the middle of the night quickly spread.

His flat, about halfway up the building, was seemingly unscathed by the ferocious fire while other flats metres away were completely blackened.

Steven Paston, 36, a freelance photographer for Press Association, was watching smoke rise from the gutted building about 8am when he saw a figure moving inside.

As he looked through his camera's viewfinder, a man poked his head out of one of the windows. Three floors above him, flames remained visible.

Mr Paston said the man did not appear to be shouting or gesturing as he watched what was happening.

"I only saw him for maybe a minute, maybe two minutes," he said. "From what I saw, he was casually just sticking his head out the window. He wasn't sticking his head out all the time.

"That section of the building hadn't been engulfed. It looked like that was the area that was fairly safe."

Several photographers captured images of a resident, possibly the same man, holding a piece of material out the window.

Mr Paston said the man he photographed was the only resident he saw, in a "small corner" of the building that remained intact.

"The entire building has gone up. I would say 80 per cent of the building is destroyed, all belongings are completely wiped out," he said.

"I think there's only about 20 per cent left of the building, where some people would obviously hopefully be able to get their belongings out - family albums, keepsakes. But everyone else, it's all gone."

Police had a cordon blocking off a huge area surrounding the building as firefighters worked, but Paston got to about 400 metres away.

He said that, as he took photos, he could hear the building creaking and groaning.

"You could hear, at times, the building making sounds like glass cracking or maybe walls just creaking," he said.

At least 1000 people who lived nearby were in the streets watching firefighters battle the blaze from about 7.30am to 9am.

A nearby church opened its doors to residents who had nowhere else to go, while hundreds of emergency vehicles blocked roads.

Paston said he had never seen such a vast fire in London before.

"I know London had riots in Tottenham a few years ago and there was a flat that got completely destroyed, but this - personally - it's probably the biggest I've seen.

"It's obviously got to come down. That building cannot be saved, basically. At some point they will have to just demolish it."

Other photographers on the scene captured a man, who appeared to be covered in soot, being carried out of the building.

As the morning progressed, authorities said they did not expect to pull any more survivors from the building.

Rescue workers were later spotted entering the building with stretchers and body bags, removing several bodies as exhausted firefighters rested nearby.

The building continued to smoulder about 16 hours after the fire began, with firefighters expected to remain at the scene for at least 24 hours.

Steve Apter from the London Fire Brigade said the blaze, which killed at least 12 people, was "an unprecedented fire in terms of scale, speed and spread".