How families tracked victims and survivors in real time during Hong Kong's Tai Po tower fire

When a fatal fire tore through seven high-rise towers in Hong Kong's Tai Po district on Wednesday, thousands of families were glued to a single webpage.

The webpage displayed a grid of coloured squares, each square representing a flat inside Wang Fuk Court. 

A red square meant residents inside were signalling SOS, or not responding, or had died. A green square flagged that the residents were safe.

By Thursday morning, more than 100 squares on the grid had turned red.

The grid also included entries on pets and the residents' situations.

Some of the entries were chilling.

In one flat on the fourth floor of Tower F, an elderly woman in her 90s had stopped responding. 

In another flat on the 18th floor in Tower B, a young child was believed to be alone at home. And on one level above, nine cats and a dog were believed to be trapped inside.

On the 27th floor of Tower E, one person was marked dead.

The system was powered by a Google form, updated almost in real time by residents, neighbours and their families.

Locals turned the spreadsheet into an interactive "SOS map", which updated far more quickly than official government briefings.

Families waiting outside the estate refreshed the page every few seconds, hoping to see a red square turn green.

For many watching online from afar, it offered the only glimpse of what might be happening.

A firefighter's grief

Among the thousands following the SOS map on Wednesday night was Raymond Cheung, a former Hong Kong firefighter who spent 18 years on the frontline before settling in Melbourne.

For him, the growing sea of red squares felt painfully familiar.

The former senior station officer in Hong Kong's International Financial Centre said seeing the entries made his chest feel heavy.

With years of experience responding to major fires, he could picture the conditions inside the towers — the temperature, the smoke, and the dangers his former colleagues were facing.

He also knew what the families waiting outside were going through.

"It's very hard to accept these numbers," he said.

Mr Cheung stayed up all night, endlessly refreshing the SOS webpage and a news website. 

He said the scale of the incident was unlike anything he had seen in Hong Kong.

While fires have spread rapidly before, they were usually contained within a single block, he said.

This time, seven towers were involved, affecting thousands of residents.

As he watched footage of flames climbing the buildings, he thought about his former colleagues rushing up the stairwells.

He worried for them, but also understood that danger had always been part of their job.

Mr Cheung said the ingenuity of Hongkongers did not surprise him. 

During past emergencies, he had seen communities mobilise technologically within hours.

"There's a strong spirit of mutual support and innovation," he said. 

"People just use whatever skills they have — like IT professionals this time — to help find missing residents."

Why the blaze became unstoppable

Authorities say the fire is now the deadliest in Hong Kong in more than 60 years. The death toll has risen to at least 55 and hundreds remain unaccounted-for.

The fire was classified as a level-five alarm — a designation not used in Hong Kong for 17 years. One firefighter, 37-year-old Ho Wai-ho, died in the rescue effort. Many more were injured.

Fire crews have reached the 17th and 18th floors of most towers, but pockets of fire continue to burn inside four buildings.

Early investigations point to a combination of factors.

Firefighters discovered that the protective netting, waterproof tarpaulin and plastic sheets surrounding the scaffolding burned far more intensely than materials approved under safety regulations.

Police have described the behaviour of these materials as unusual.

Inside the one tower not directly burned, investigators found styrofoam panels glued to window frames, blocking ventilation openings.

The material ignited easily and allowed flames and heat to travel through corridors and into units far from the original ignition point.

Mr Cheung said bamboo scaffolding — long used in Hong Kong construction — can catch fire quickly, but cautioned against attributing the fire to the material alone.

He said any breach of construction safety regulations could have contributed to the spread, and investigators will need time to determine what went wrong.

He added that a 31-storey tower was considered modest by local standards in one of the world's most densely populated cities.

Beijing confirmed that President Xi Jinping was briefed and had immediately instructed Chinese authorities to support Hong Kong's rescue, medical and recovery operations.

Residents in the neighbouring city of Shenzhen also reported seeing large numbers of fire trucks and medical teams rushing to the border checkpoint, standing by to provide support.

Many in the diaspora 'couldn't sleep'

Jane Poon from Australia–Hong Kong Link said the fire dominated community chat groups as soon as the first images appeared.

Ms Poon, who once lived near the seven towers in Tai Po, said the sense of helplessness grew as flames engulfed the towers.

"Everyone became very worried," she said.

In a statement from her organisation, Ms Poon and her colleagues expressed solidarity with families in Hong Kong and around the world.

They called on authorities for truth, accountability, and a fully transparent investigation of how the disaster unfolded.

Mr Cheung said the fire also took an emotional toll on the diaspora, who hoped the tally of red squares on the SOS map did not spread further.