The fire alarm systems on some floors in a Hong Kong skyscraper were shut down because of major renovation works, authorities revealed in the aftermath of a blaze in the building that trapped hundreds of occupants on its rooftop, with rescuers later evacuating 1,269 people.

The fire at the 40-storey World Trade Centre on Gloucester Road, Causeway Bay, broke out during the lunchtime rush and forced many to seek safety on the rooftop.

Viral videos also showed dozens of people, including the elderly, waiting for evacuation at an open-air area on the fifth floor. According to the Information Services Department, the flames were mostly put out by 4.30pm.

Thirteen people aged 25 to 82, comprising a man and 12 women, complained of feeling unwell, with 10 of them inhaling heavy smoke and three suffering sprains.

At an evening press conference, Ng Yau-sheung, senior divisional officer from the Fire Services Department, said: “One of the biggest difficulties we encountered was that the floor area of the building was large and we received multiple calls for help ... That’s why we upgraded the fire to level three.”

Ng added the blaze started on the first and second floors of the building, with signs it originated from an electrical switch room.

He said the fire installations in the building – including auto-sprinklers, manual alarm systems and detectors – were shut down due to major renovations being carried out from the first to fifth floors.

“If the system is under repair, it’s possible the contractor will shut down the area affected,” Ng said, adding that alarms on other floors were unaffected.

He said fire services were investigating and would follow up with the building operator.

Sun Hung Kai Properties, which owns the building, said its service centre had immediately assisted emergency teams to evacuate tenants and customers. It expressed sympathy for those who were affected.

The sections below detail out how events unfolded throughout the day:

Hundreds gathered on the rooftop of the Causeway Bay skyscraper.

Waiting for rooftop rescue

Zac Chan, 25, was at Jaffe Road near the police cordon because his roommate was stuck on the rooftop waiting to be evacuated.

“He said there were around 100 people on the rooftop and have been waiting for about an hour for rescue,” said Chan, who rushed here from his workplace in Admiralty. “He’s quite calm and we are keeping in touch.”

Office worker Ernest Chan was one of those evacuated to the roof, but made his way down using the staircase after a long wait.

“Initially we were walking down but at around the 17th floor we heard that there’s heavy smoke, so we decided to head to the roof instead,” said the 28-year-old. “But we waited for too long and the visibility seemed clear, so we walked down again. If we didn’t make this call we would still be waiting upstairs.”

Lucas Lam, 25, who works inside the building, managed to escape on his own from the site at 3pm with a group of his colleagues. He said firefighters had told him the blaze was “under control”.

“As we work on the 32nd floor, at first we remained on the [rooftop] to stay away from the heavy smoke,” Lam said, adding that he and colleagues later found some stairs that offered them a safe passage out.

Lam added that he saw a crowd of more than 100, including the elderly, on the rooftop. They were told to wait for up to two hours for smoke to clear, but Lam and others decided to find escape routes on their own because “we can’t stay that long”.

At least 13 injured

As of 4.30pm a least 13 people were injured or complained of feeling unwell. The group comprised one man and 12 women. Six of them were sent to Pamela Youde Nethersole Eastern Hospital in Chai Wan for treatment, while five were taken to Queen Mary Hospital in Pok Fu Lam. The remaining two were sent to Ruttonjee Hospital in Wan Chai.

Authorities later said a woman, 60, was in critical condition in Ruttonjee Hospital.

The Fire Services Department’s mobile casualty treatment centre had arrived at the scene shortly after 2pm.

‘It’s like a maze inside’

Renovation worker James Ng was based on the third floor of the building which was blocked off to the public.

He said there were only two ways out of the building because of the ongoing renovations.

The number of lifts servicing the restaurant floors was also halved from four to two, he added.

“All the shops on the third floor are boarded up, some escalators only run in one direction while others are not functioning,” he said. “It’s like a maze inside. You will get lost if you’re not familiar with the place.”

People seek safety on the roof of the World Trade Centre.

Construction worker Mr Yeung, who is in his fifties, said he noticed smoke coming out from the wiring trough on the fifth floor where he was working.

“Once we saw the smoke, we stopped and evacuated immediately,” he said. “We got out before the smoke spread to higher floors.”

Kelly Chow, who works in a tour agency on the 22nd level, said she made her way up to the rooftop and waited for instructions from fire services.

“People were rushing up the staircase towards the rooftop. When some attempted to open the door to a stairway on the 30th floor, more smoke rushed in,” she said.

“After two hours we were instructed to go down to the 38th floor and take the lift down in groups of 14. One or two people needed oxygen masks.”

People and smoke emerge from building

On Jaffe Road, which leads to the rear of the World Trade Centre, people were seen at about 2pm streaming out of the building.

They were helped by emergency services personnel, with some being taken away on a stretcher.

Smoke could be seen wafting out of the building on the ground floor, as well as the higher levels.

The Post saw a woman being escorted out of the building wearing an emergency smoke hood, before she was carried into an ambulance on a stretcher.

Restaurant manager recounts escape

Ms Gu is the manager of a 12th floor Chinese restaurant which was busy serving 80 diners when news of the fire emerged.

She said that, as of lunchtime, three of her staff were still stuck in the building.

“At around 12.45pm we started noticing smoke coming from the stairwell,” Gu said.

“We called the management hotline multiple times but there was no response.

“We quickly gathered the customers and grabbed some towels and evacuated. We had to bend low as the smoke was swelling up in the staircase.”

Mr Fu, 28, a diner in a restaurant on the 13th floor, said that he noticed smoke emanating from the lift lobby at about 1pm. “There was no fire alarm,” he said. “We just took wet towels and went down the staircase on our own accord.”

Hundreds trapped on rooftop

As of about 2pm, police said more than 300 people were trapped on the rooftop of the building and another 160 had been evacuated.

Firefighters were seen using an extendable ladder at 1.45pm to rescue those who were trapped in an open-air area section of the building on the fifth floor.

Office workers and restaurant-goers were said to be among those still in the building, which operates as a mall and office tower complex.

Authorities believe fire started in switch room

Police said preliminary investigation suggested the blaze broke out in an electrical switch room in the first floor of the shopping mall, before spreading to scaffolding that covered part of the building.

Smoke then entered the shopping centre itself and rear staircases.

Shortly after 1pm, the fire was upgraded to a level three incident. The severity of blazes in the city is graded on a scale of one to five, with the latter the most serious.

Shopping mall renovation

The shopping centre, including its basement car park, has been undergoing massive renovation works for several months.

The lower floors of the building, which is owned by Sun Hung Kai Properties, have been surrounded with scaffolding.

All the shops had been vacated for renovation. Only restaurants between the sixth and 13th floors, as well as office space between the 14th and 38th floors, were still in operation.

Smoke can be seen in a restaurant in the building.

Dozens trapped in restaurants

A police spokesman said they had received multiple calls about the fire, reporting the rear staircases of the building were filled with dense smoke.

He said initial information showed that about 100 or so had been evacuated to a fifth floor open-air area section of the building.

However, as of about 1pm, dozens were still trapped in restaurants in the shopping centre.

The fire broke out at lunchtime on Wednesday.

Firefighter teams battle blaze

Emergency services were alerted to the fire at 12.37pm on Wednesday.

A government spokeswoman said at about 1pm that firefighters were fighting the blaze with two water jets. Two teams from the service equipped with breathing apparatus were also deployed, the spokeswoman added.

According to information on the website of the Fire Services Department, buildings taller than 25 storeys but not exceeding 40 can count the main roof as a refuge floor – a protected area for building occupants to gather temporarily and rest in the event of a fire.

A refuge floor should provide adequate cross-ventilation and be equipped with fire service installation and equipment as required under official guidelines.