A fire tore through a block of flats this afternoon sending scorching panels of glass tumbling 100s of metres to the ground.
Some 125 firefighters descended on the tower block in Whitechapel High Street, east London, earlier this afternoon.
The blaze broke out on the 17th floor of the 21-storey Relay Building, sparking an evacuation of around 60 people.
Firefighters rescued one woman who was trapped in the building by using a fire escape hood.
London Fire Brigade Group Commander Jim Flint said the woman was rushed to hospital, although she was not seriously injured.
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Crews used a 64-metre ladder and two cranes to reach the blaze.
It's understood that all residents have now been evacuated from the building.
Residents were forced to send WhatsApp messages and knock on their neighbours' doors as people could not hear the fire alarm, MyLondon reports.
Andrew Meikle, who lives on the 9th floor, told MyLondon: “I can’t believe we had to message each other on WhatsApp groups and knock on each other’s doors just to tell each other that there was a huge fire in our own building.”
An anonymous local resident, 61, who is a security officer that lives on the seventh floor, has lived in the building since 2012.
They said: “I can’t understand why the alarms didn’t go off, it’s ridiculous. I had just come off the night shift and I was asleep - if it wasn’t for neighbours knocking on my door I wouldn’t have heard anything - I’m asthmatic and I live alone so that’s another concern.
"It’s a miracle there were no fatalities. They (building owners) need to get their act together - I haven’t had electricity in my bathroom for 8 weeks.”
Witnesses watching the blaze this afternoon reported seeing rows of "blown out" windows as the inferno scorched the ceilings inside.
Owen Willis told The Mirror: "We can see a row of windows blown out with fire burning on the ceilings still.
"It’s very windy so it looks like the smoke and flames are blowing all over the place.
"Seems to be dying down a bit although that’s just what we can see from outside."
Another eyewitness, Alexandra Capaldi, 18, who works in a cafe on Brick Lane, was walking home from work at the time of the fire.
She told MyLondon: “It was chaos - there was glass falling from the building and people were screaming.”
Witnesses have praised the London Fire Brigade and the rest of London's emergency services for their efforts in tackling the blaze.
Revealing that firefighters had rescued a trapped woman, a spokesman for London Fire Brigade said: "A woman was trapped by the fire.
"999 control officers gave her advice & firefighters rescued her by using a fire escape hood. Incredible professionalism by all avoided serious injuries."
Lynn Ling, 25, a London School of Economics student from China who lives on the 20th floor with her husband Yuri, said the incident had been “very scary”.
Ms Ling, who was wearing a silver security blanket because she forgot her coat in the scramble to evacuate, was alerted to the fire by a friend who called her from the street at about it 4.30pm.
She said: “I did not hear an alarm. I think there was a fire alarm on the ground floor but I could not hear it clearly on the 20th.
"I went out of my door but I found there was smoke in the corridor so I went downstairs. I forgot to take my coat. It was very scary.”
She added that a fireman on the 19th floor was knocking on doors telling people to leave.
“He said, ‘Don’t be scared’,” she added. “They were trying to protect us. He was nice.”
The 25-year-old said that when she was on her way down, a group of firemen “were about to go upstairs”.
Ms Ling said she did not know what had started the fire and added she was “very worried” about their possessions.
Her husband added they are not sure they will get back into their flat tonight and will stay with a friend.
The tower block is split into two sections - with the lower floors being used as offices while the top floors - where the fire broke out - are residential.
A witness tweeted: "Amazing effort from Fire Service to put out the fire in Aldgate East #Whitechapel"
Another commented: "@LondonFire you did a great job there, Thank you to all the crews!"
A MyLondon reporter at the scene has confirmed the blaze has now been put out, and that the flames left a "charred black hole" on the outside of the building.
Earlier the reporter detailed which properties the fire had hit.
She said: "The only flames now are on the balcony. It has affected the fifth-to-top floor and the floor above, as well as the balcony on that floor and the one above.
"Three windows can be seen broken on one side, and four on the other. The fire appears to have spread from one balcony and upwards. Lots of smashed glass can be seen on the road, especially outside Aldgate East station and Paddy Power."
A nearby building has also been evacuated with the residents having been taken to nearby park for safety.
Earlier today another eye-witness tweeted a video of raging orange flames climbing up the side of the tower as clouds of black smoke billowed into the sky.
Captioning the video, he said could see "huge" glass panels falling "100s of metres" from the tower.
A Tower Hamlets Enforcement Offcer told a reporter at the scene he believes everyone has now been evacuated from the building.
The Metropolitan Police confirmed the building is being evacuated.
A spokesperson said: "We were called to the scene at 1555 to reports of a fire on Whitechapel High Street by the emergency services.
"The building is being evacuated."
The London Ambulance Service is also at the scene.
In a statement, they said: "We are responding to a fire on #Whitechapel High Street with our emergency service colleagues.
"If you are in the local area, please try and stay indoors and keep windows and doors closed. More updates to follow"
The London Fire Brigade broke news of the fire on Twitter this afternoon.
On its website the fire brigade wrote: "Twenty fire engines and around 125 firefighters have been called to a fire at a block of flats and offices on Whitechapel High Street.
"Crews are tackling a fire on the 17th floor of a 21-storey building. The Brigade's 64m ladder has been mobilised to the incident.
"The Brigade's 999 Control Officers have taken more than 50 calls to the blaze.
"The Brigade was called at 3.53pm. Fire crews from Whitechapel, Shoreditch, Dowgate, Bethnal Green, Dockhead, Old Kent Road, Islington and surrounding fire stations are at the scene.
"The cause of the fire is not known at this stage."
