(Karla Adam,Sarah Parnass/The Washington Post)

Sajad Jamalvatan was at the movies Tuesday night when he got a call from his panicked mother. Come home quickly, she begged, adding, “The building is on fire!”

A few minutes later, the 22-year-old biomedical engineering student rounded the corner to see Grenfell Tower transforming into an inferno.

“As soon as I arrived, someone pointed and said: ‘Someone is jumping! Someone is jumping!’ ” he recounted near the building Wednesday, with the smell of smoke lingering in the air. He estimated the person jumped from the 16th or 17th floor of the 24-story tower.

That is not the kind of fall you can survive. The number of dead was at least 12 — with dozens more injured and authorities warning that the death toll could rise.

Witnesses described children — including a baby — being thrown out of windows in the hopes that they would be caught by onlookers below. Others saw young children banging frantically on windows before disappearing behind a thick blanket of smoke. 

The fire-damaged floors of the 24-story residential Grenfell Tower in London on Wednesday. (Carl Court/Getty Images)

“Seeing people die in front of you . . . ” Jamalvatan said as his voice trailed off and he stared hard at the sidewalk.

He said the blaze had advanced quickly and that the alarms did not appear to have been triggered. “When I arrived, there were 10 flats on fire,” he said. “After that, the whole building was on fire.”

He snapped his fingers. “It went like that.”

Accounts such as his added to suspicions that construction material could have contributed to the blaze that engulfed the modestly priced units overlooking one of Britain’s richest neighborhoods.

The residents association from the apartment tower had previously warned that it was a potential fire risk — they highlighted their concerns in a blog post last year — and there was palpable anger among survivors that more could have been done to prevent the fire.

Some complained that the fire alarms did not work properly. Others said that a single staircase in the middle of the building was an inadequate escape route for the building’s 500-plus residents. Still others claimed that the building managers did things on the cheap.

(Amirali Alfideh)

London Fire Commissioner Dany Cotton called the fire “unprecedented” and said an investigation was underway.

At a community center near the apartment building, hundreds of people gathered in hopes of locating missing friends and relatives — including some Muslim residents who were participating in the special evening meal that takes place during the holy month of Ramadan.

Concerned Londoners arrived in droves at various collection points, carrying plastic shopping bags sagging with food, diapers, toiletries and blankets.

Churches and mosques offered food and shelter to those affected by the blaze.

Ahmed Chellat, a retired 60-year-old, was at a community center looking for his brother-in-law, his wife and their three children, the youngest of whom was just 8. He said that he spoke to his brother-in-law’s wife at 1:45 a.m. and that she was still in their apartment on the 21st floor.

When he asked her why they were not rushing out of the building, she responded, “They are telling us to stay in — they are asking us to cover doors with towels,” he recalled.

Half an hour later, he called back. “The last thing she said was smoke was coming heavily into the flat.”

He later told television reporters that he had reconnected with his relatives. 

Many residents said the building had recently been refurbished and fitted with plastic panels that they believed helped the fire spread quickly. “You could hear it cracking, hear it flying,” Chellat said. “If it was brick it would not have caught fire as quickly.”

Flammable exterior cladding has been blamed for several rapid fires at high-rises around the world — including several blazes in Dubai.

Just before New Year’s celebrations to welcome 2016, a fire raced through the 63-story Address hotel in Dubai as millions of people watched television coverage of the festivities at the nearby Burj Khalifa, the world’s tallest building. A handful of people suffered injuries.

Soon after, Dubai civil defense authorities ordered new fire safety regulations that include installation of fire-resistant cladding.

Mohamed Bouye, a 44-year-old manager, was touring the local community centers in London trying to find his friend who lived on the 18th floor of the building.

He watched the fire burn throughout the night. When he first arrived at the tower, shortly after 1 a.m., it looked as if the blaze could be contained to one section of the structure, he said. He recalled even seeing one man casually leaning over the railing of the building, as if there was no imminent danger. But things changed quickly.

“The flames went from the ninth floor to the 27th floor in 10 minutes,” he said. “There were then screams. ‘Help us!’ I saw two people jump, two bodies flying down. They were between floors 10 and 15. Other people told me they saw people jumping from the other side of the building.”

Christine Umeh, 35, was awakened about 3 a.m. by the whirring of helicopters. When she looked out of her building, which faces the tower, she saw helpless residents on the top floors flickering their lights on and off, on and off.

“It’s like they were saying: ‘Just help me. I’m here. Try to help me,’ ” she said. “It was like an SOS signal.”