Among the key questions: Did a “stay put” fire protocol, which told people to remain in their apartments until firefighters arrived, delay residents’ escape? What role did aluminum exterior cladding, installed as part of a renovation completed last year, play in the fire’s rapid spread? And should older buildings like Grenfell Tower, completed in 1974, have to be retrofitted with sprinklers and centralized alarm systems?
“The full scale of the tragedy is becoming clear, and there are pressing questions which demand urgent answers,” said Mr. Khan, who refrained from assigning blame. “In light of concerns about the safety of other tower blocks that have been similarly refurbished, the inquiry needs to produce an interim report by the end of this summer at the latest.”
The cause of the fire is still under investigation, but the police have ruled out terrorism.
Firefighters said Wednesday afternoon that there was no hope of finding additional survivors, but the government has appealed for residents to call a hotline as they try to account for everyone who might have been in the building. Among those still missing were a young Italian couple who moved to Grenfell Tower several months ago, Italian news outlets reported. The building, in the North Kensington neighborhood, housed people from many countries, including Eritrea, the Philippines, Somalia and Sudan.
Investigators continued to comb through the wreckage on Thursday with help from search dogs. Commissioner Dany Cotton of the London Fire Brigade said firefighters had searched all 24 floors of the tower, but that safety concerns had circumscribed the search in some areas, including the top floors, where, she said, “very small pockets of fire” remained.
Mrs. May, already under pressure after a series of terrorist attacks and the election last week in which her Conservative Party lost its majority, went on Thursday to the area where the fire took place, as did the leader of the opposition Labour Party, Jeremy Corbyn.
The Grenfell Action Group, an association of residents of Grenfell Tower, had complained for years that the local council, the Royal Borough of Kensington and Chelsea, which owns the building, and the company that managed the property had repeatedly ignored their concerns that the building posed a fire hazard.
Survivors of the fire recounted that they first learned their lives were in danger through word of mouth.
Eddie Daffarn, a 16th-floor resident who is a member of the Grenfell Action Group, said he was alerted to the fire by a neighbor’s smoke detector.
“The only alarm that went off was my neighbor’s smoke alarm. I thought he had burned some chips,” he said, referring to French fries. “I opened the door and there was smoke, loads of smoke, so then I closed it and thought: This is a real fire, not my mate’s chip pan.”
A friend who lived on the fifth floor phoned and urged him to flee, he said.
“I wrapped a towel around me, and opened the door,” Mr. Daffarn recalled. “The smoke was so thick and heavy I couldn’t see anything. I thought: ‘This is me, I’m a goner.’”
He finally descended and was helped by a firefighter.
“I am lucky to be alive,” he said.
Meriam Antur, who lived on the 19th floor of the tower, was one of many residents who said she was told to stay put, despite sirens and smoke that created panic. “My friend came in and said we had to wait for the firemen and couldn’t go down,” she said, recalling that as smoke entered the apartment, she put a wet towel under the door and began to pray.
“My children were crying, and I’m pregnant,” she said, clasping her belly. “I was so scared. I thought we were going to die.”
Matthew Needham-Laing, an architect and engineering lawyer who specializes in cases dealing with building defects, said the dark smoke that had engulfed the building was a telltale sign of burning cladding material.
“It looks to me like a cladding fire,” he said. The material in the cladding, he added, is “flame retardant, so it doesn’t catch fire as easily, but the temperatures you’re talking about are often 900, 1,000 degrees centigrade, and in those conditions, any material will generally burn.”
Sian Berry, chairwoman of the Housing Committee of the London Assembly, said in an interview that she was concerned that fire-risk assessments in high-rise buildings were less exacting than they should be.
“It used to be that the fire service would routinely undertake these assessments, but now building owners decide when to do them, and they don’t always do them often enough,” she said.
She added that centralized fire alarm systems were not required for residential buildings since they required constant monitoring to be effective. Grenfell Tower did not have one.
The building also lacked a sprinkler system; regulations requiring such systems came into place decades after it was completed.
After six people died and more than 20 were injured in the 2009 tower block fire, a parliamentary group called for a review of fire safety rules, while an inquest advised the government to require that older buildings be retrofitted with sprinklers. That did not happen.
Ms. Berry questioned the “stay put” policy.
She noted that an inquiry into the fire at the Camberwell block, Lakanal House, had concluded that residents had stayed 30 minutes longer than they should have and that deaths could have been prevented — a lesson that appears not to have been heeded by those managing fire safety at Grenfell Tower.
“If you have good fire resistance between flats, there is less risk if you stay in place then if everyone runs out of the building at the same time,” she said. “But this shouldn’t be applied in a hard and fast manner, even after there is danger.”
David Lammy, a Labour lawmaker representing Tottenham, in Northeast London, told the BBC that he considered the fire to be “corporate manslaughter.” “This is the richest borough in our country treating its citizens in this way, and we should call it what it is,” he said. “It is corporate manslaughter. That’s what it is. And there should be arrests made, frankly. It is an outrage.”
He said that after knocking on housing estate doors across the country during recent elections, he had seen that many buildings had antiquated fire standards and poor conditions.
“Those ’70s buildings, many of them should be demolished,” he told the BBC. “They have not got easy fire escapes. They have got no sprinklers. It is totally, totally unacceptable in Britain that this is allowed to happen and that people lose their lives in this way. People should be held to account.”