JUDY WOODRUFF: And now to the day's other major story. It is in London, where a fast-moving fire engulfed a high-rise apartment building. It killed at least 12 people and injured scores.

We have a report from Dan Rivers of Independent Television News, and with a warning: Some of the images and sounds may be disturbing.

DAN RIVERS: With horrifying ferocity, the fire consumed Grenfell Tower in minutes, a 24-floor inferno from which there was no escape for some.

Trapped by smoke and flames, residents signaled their plight from on high as the building disintegrated around them.

On this mobile phone footage, the cries for help are chilling.

MAN: Help! Help!

MAN: We saw people looking out of the windows, screaming help, screaming, help, help, flashing their lights and everything. And now all those windows, people are gone, literally gone.

MAN: I saw one person trying to jump out. One actually jumped out, and obviously what happened. It's just a nightmare.

DAN RIVERS: The streets around Grenfell Tower were soon full of those who escaped its flames, children among those suffering from the acrid fumes.

An exhausted little girl is cradled as the shock and bewilderment sink in. Many here have lost everything. Some are still unsure what's happened to neighbors, friends, loved ones.

And, above them, the fire raged on. As the sky lightened, the flames continued to devour the building. This was the view from the SOUTH BANK, the plume of smoke visible for 20 miles. With daylight, stories of extraordinary escape started to emerge.

SAMIRA LAMRANI, Witness: A lady appeared at the window, gesturing, body language, from what she was saying, I'm about to throw my baby, please catch the baby. And the baby, I think, was wrapped in some sort of bed sheet, blanket. And she threw the baby. As the baby came down — and this was about approximately from the ninth or 10th floor — a member of the public, a gentleman ran forward and miraculously grabbed the baby.

And, like I said, above you, from the left, from the right, mostly kids, it was harrowing, torturing screams for help, young kids. And I think also, where the fire was now spread, people were reaching out from the front window, trying to grasp a bit of fresh air, trying to breathe in like they were struggling.

And there were, at one point, one window about four or five heads all squeezing their heads through. It was honestly like a horror movie.

DAN RIVERS: Some had knotted sheets together in an attempt to escape. But even this left them several floors short of safety.

WOMAN: People were jumping off buildings. People were screaming, saying, help me, help me, help me.

DAN RIVERS: The cause of the fire is unknown, but one resident claims it spread from her neighbor's flat, possibly a faulty appliance.

WOMAN: The fire started from the kitchen, but I don't know exactly — from which problem, I don't know. But it was from the kitchen, because the flat door was open.

DAN RIVERS: It's already clear the death toll will be significant. Up to 600 people lived in Grenfell House in 120 flats. For those who were on the very upper floors, the odds of survival seem slim.

Those fighting the fire confirmed today how challenging it's been to extinguish.

MAN: This was an unprecedented fire in terms of scale, speed, and spread. And just to reiterate that point, the incident continues to be a challenging incident for us.

DAN RIVERS: There is speculation a gap behind a recently added external cladding may have created a chimney effect, allowing the flames to spread.

Some had to wait all night before they escaped. This man was still calling for help six hours after the fire started. At times, he disappeared into clouds of smoke, but, incredibly, he did finally make it out, one of 65 rescued from Grenfell Tower today.

Tonight, while most of the flames have been put out, the charred shell of the tower block continues to smolder. It may be days before the final death toll is known, and much longer before the cause of this tragedy is pinpointed.

JUDY WOODRUFF: Prime Minister Theresa May promised a full investigation, and the British government ordered safety checks at other high-rises undergoing renovations.