A huge number of firefighters rushed to a blaze on Friday in a tower block thought to have similar cladding to that of Grenfell Tower.
Emergency services were called to a high-rise in New Providence Wharf in Poplar, east London, at around 9am.
Pictures from the scene showed smoke billowing from the building, with firefighters on ladders trying to douse the flames.
The London Fire Brigade (LFB) said around 125 firefighters were sent to Fairmont Avenue, and 25 fire engines.
The London Ambulance Service (LAS) initially said it had “treated a number of people”.
It later emerged two men were taken to hospital suffering the effects of smoke inhalation.
A further 38 adults and four children were treated at the scene by paramedics for shock and smoke inhalation.
Reports say the cladding in the building is made of a similar material to Grenfell Tower, where 72 people lost their lives in 2017.
The high-rise is said to feature aluminium composite material (ACM), which is at the centre of a housing scandal over fire risks.
The Grenfell Tower tragedy shocked the nation, sparking an inquiry and ongoing conversations over the safety of some high-rise buildings.
Residents in Poplar revealed after the blaze that fire alarms did not go off until the fire was already spreading in the block.
Kate Gibson, 31, who works as a consultant in the City and lives in the flat next door to where the fire began, said: “We live next door to the flat which caught fire – it started on the eighth and then moved up to the 10th floor.
“I was at my desk in my bedroom just working away when I saw black smoke out my front window and then someone shouted ‘fire!’
“I opened my front door and saw a lot of smoke in the corridor and so slammed the door.
“I have two guinea pigs – Norman and Theo, so I grabbed them and ran out of the building. There is no way I’m leaving them behind.
“A security guard was running up the stairs to try and alert people.”
She added: “I served in the army for three-and-a-half years so I thought I would be okay, but my legs were shaking because of the cladding we’ve got on the building.
“It’s the same as Grenfell.
“There were no alarms going off until I got down to the fourth floor – which is crazy.”
Marlene Morais, 42, a fashion designer, said: “I live in a building next door and saw a lot of police cars and ambulances, storming in.
“A fire truck crashed into a mental railing on the roundabout because they were in such a rush.
“I went out of the building and could see all these people running and shouting.
“I could see all the smoke coming from the building and a little bit of fire.
“The Fire Brigade put a ladder all the way up – I think it was like the eighth floor.
“They were stood on top of the ladder spraying water onto the flames.
“I saw all the fire people coming in and out and there faces were all red from the heat.
“There were some people wearing green, so there was a few casualties.
“I was imaging all the people above who could have been sleeping or maybe they fainted because of all the smoke.
“It was really scary, I had to take my child to her dad’s because she doesn’t want to be here and see all this.”
A spokesperson for the LFB said parts of the eighth, ninth and 10th floors of the 19-storey building in Poplar were set alight.
The cause of the fire is under investigation.
A full LFB statement reads: “Twenty fire engines and around 125 firefighters were called to a fire at a block of flats on Fairmont Avenue in Poplar.
“Parts of the eighth, ninth and 10th floors of a 19-storey block were alight.
“Firefighters wearing breathing apparatus have carried out multiple rescues.
“Two men have been taken to hospital suffering smoke inhalation.
“A further 38 adults and four children have been treated at the scene by London Ambulance Service crews for shock and smoke inhalation.”
A LAS spokesperson added: “We were called at 9.05am this morning (May 7) to reports of a fire on Fairmont Avenue, E14.
“We have sent a number of resources, including ambulance crews, clinical team managers, an incident response officer, a command support vehicle, an emergency planning and resilience officer, and our hazardous area response teams.
“They have treated a number of people and remain at the scene, where they are working with other emergency services.”
Matt Wrack, general secretary of the Fire Brigades Union, said of the Poplar fire: “It is extremely alarming to see another high-rise building in the heart of London light up in flames.
“A huge thank you to the firefighters who responded and got the fire under control so quickly and our thoughts are with all of those affected.
“It should shame this government that four years on from Grenfell there are people across the country living in buildings wrapped in flammable cladding.
“Time and time again we’ve warned that another Grenfell could be just around the corner unless they prioritise making people’s homes safe.
“The pace of removing flammable cladding has been glacial and it’s putting people’s lives at risk.
“The government must intervene and take quick and decisive action to end our building safety crisis once and for all.”
A spokesman for the Ministry of Housing, Communities and Local Government thanked the emergency services for putting the fire out and said it is too early to speculate on the cause of the blaze.
The MHCLG spokesman, who said the department is working closely with the fire brigade, added: “The building has received £8m government funding to remove unsafe ACM cladding – this work was set to take place on Monday and we have been in regular contact with Ballymore over the last two years to make progress, including publicly naming Landor, their subsidiary, as one of the companies that has consistently failed to take action. Ministers have met Ballymore repeatedly to urge action.
“We are spending £5bn to fully fund the replacement of all unsafe cladding in the highest risk buildings and are making the biggest improvements to building safety in a generation.
“It is essential that building owners take swift action to remediate defective cladding and the government will fund every eligible application.
“Workers are on site in 95% of buildings identified as having ACM cladding at the beginning of 2020 and we expect that work to be completed at pace in the coming months.”