The day before, as roaring flames edged closer, the 69-year-old had run through her apartment block looking for her neighbour, who she knew lived alone and used a wheelchair.

She got her outside before the inferno engulfed their residential estate, killing at least 44 people and leaving hundreds missing.

On Thursday, Kwok and others in her community were mobilising to track down the hundreds authorities said were still missing, creating WhatsApp groups and an app to try to locate those unaccounted for.

"I saw (the flames) draw closer, it was burning red and my heart was burning too," said Kwok, describing how she had rushed through the building knocking on doors to warn people.

She said she had not heard a fire alarm at any point during the ordeal.

As the sun rose over the smouldering towers of Wang Fuk Court on Thursday, displaced residents had already spontaneously begun organising themselves to deal with the aftermath.

Hundreds in the neighbourhood sprang into action overnight, forming a decentralised but energetic community of helpers.

"There are at least three (people) we can't reach, we are very worried for them, and I'm going to the community centre later to continue searching," Kwok said.

- 'Help needed' -

After what many said had been a sleepless night, crowds gathered on parks and walkways in the northern district of Tai Po to bear witness to the still-flickering remains of the estate.

Residents circulated an online spreadsheet -- which someone quickly converted into a slick web app -- where people could mark themselves safe.

On Thursday morning, dozens of spreadsheet cells were still highlighted red, meaning "help needed".

A 70-year-old woman surnamed Leung, who lives next to Wang Fuk Court, said she had been unable to reach a friend who lived in one of the stricken high-rises.

"I'm so worried, I kept calling but it didn't connect," said Leung, who was among those evacuated as a precaution and spent the night in a temporary shelter.

"I came back at five in the morning because I couldn't sleep," she added as she joined the crowd watching the fire, the smell of smoke lingering in the air.

Volunteers gave firefighters bananas and energy drinks, and provided clothes, chargers, food and hot water bottles to those displaced.

Some residents formed human chains in the early hours of Thursday to transport supplies hand-to-hand, according to local media.

Dozens of people gathered at an open-air podium -- usually a favourite spot for the elderly to spend a leisurely afternoon -- to organise donated clothing.

A 24-year-old student surnamed Zhang said she had travelled more than an hour by train to volunteer.

"I felt terrible (watching the news)," she told AFP as she folded clothes.

"Having one more person to help is always better, maybe this is to soothe my sense of pain."