Medics treating those affected by the Grenfell Tower fire heard harrowing stories of how people managed to escape, a senior doctor has said.
Duncan Bew, clinical director of the major trauma centre at King's College Hospital, said some of his patients had clung to banisters to feel their way down 20 flights of stairs after fearing they were about to die.
Others had tried to save other families on their way towards the tower's exit.
King's initially received 12 patients following last week's fire. It is still treating seven people, five of whom remain in critical care.
Mr Bew said some patients still in hospital face a long recovery of weeks and possibly months.
A number of people are being kept deliberately unconscious to help them recover from the effects of smoke inhalation.
Mr Bew said King's declared a major incident shortly after it became aware of the fire and had potentially been expecting "hundreds" of patients.
"We knew there were lots of flats and that many of these were multi-occupancy," he said.
"We thought this might escalate from a major incident to a mass casualty event, with us receiving hundreds of patients."
He said staff expected to see a range of injuries, including burns, smoke inhalation and "people falling from a height, from jumping from windows."
Medics were also mindful of the potential for cyanide poisoning from old furniture going up in flames.
Most of those arriving at hospital were conscious and were a mixture of men, women and children, he said.
Almost all were suffering the effects of smoke inhalation, with very few having burns.
Mr Bew said staff became saddened when they realised they were actually going to receive a small number of patients, which meant many more people were still trapped inside the tower.
"We were ready to receive many more casualties," he said. "We knew there were many more people in the building.
"As time went on and we realised that we weren't going to receive those casualties, it was very sad.
"The people at the scene had stayed in their flats because that's what they were told to do, but the flames were coming up the external panels, to their windows and to their homes.
"They stayed there in good faith, but the agony was that the emergency services were not going to be able to reach everybody.
"We had patients who had saved their own families but had also tried to save other families as well.
"They had to make a very difficult decision. People went into the stairwells and went into toxic smoke.
"Some of them went down 20 flights of stairs. There was this intense heat and they were feeling their way down banisters.
"I think people who escaped felt that they were going to die and that the only way to stay alive was to go through the smoke."
Mr Bew said inhaling smoke can burn the mouth, airways and lungs.
The toxins can also affect the functioning of the lungs so that "breathing becomes much more difficult".
He said some patients across London had to be intubated and put on ventilators to try to avert the risk of suffocation.
He said such situations could change quickly, adding: "Some patients can walk into the department but then they go on to need this kind of ventilation support."
Staff also had to remove clothes from patients to stop the vapours making things worse.
He said: "Many of the people who have survived will go on to make a good recovery, but how many will have life-changing injuries remains to be seen.
"It may take weeks and months for some patients to recover physically.
"In terms of psychological impact, it may take longer."
Mr Bew said the current burden of injury from the fire and the death toll "is extremely conservative".
He added: "It's remarkable that none of our first responders were not killed."
Mr Bew said staff at King's were made aware of the psychological support on offer to them when treating patients from incidents such as Grenfell and recent terrorist attacks.
He said the senior team worked to "de-stigmatise" anything around stress and the obvious psychological impact on staff.
While patients may experience survivor's guilt, staff could also experience something similar, he said.
This may include guilt that they were not on the shift to help, or were on annual leave.
Mr Bew said London's hospitals are continuously learning from incidents such as Grenfell and terrorist attacks.
He said there has been a "huge amount of preparedness", including with NHS England, to deal with such events.