“An investigation into the source of the spark that ignited the bags is still under way,” the insider said, adding that a discarded cigarette butt from a public corridor on an upper floor of the building had been listed as a possible clue.

He said cigarette butts could be found in public areas on almost every floor of the building that had 35 guest houses and dozens of subdivided flats.

The source said an initial investigation of the tragic blaze had not found signs of arson or any criminal elements.

But if a discarded cigarette butt was determined to be the source of the fire, the smoker involved could face prosecution for manslaughter, the insider added.

03:18

Hong Kong fire kills 5, injures dozens in Kowloon commercial and residential building

Hong Kong fire kills 5, injures dozens in Kowloon commercial and residential building

The bottom of the lightwell was flooded with ankle-deep water after firefighters took 2½ hours to douse the flames on Wednesday.

Detectives from the Kowloon West regional crime unit will continue to work with government chemists to gather evidence from the scene.

The source said dozens of crime-squad officers were deployed to carry out door-to-door inquiries, talk to witnesses and check surveillance camera footage.

Three men and two women were pronounced dead in hospital and 43 others were injured by the blaze. Three of the injured were treated at the scene and did not need hospital treatment.

As of 10pm on Thursday, six of the injured were in a critical condition in four public hospitals. The condition of a baby girl improved from critical to serious, according to a government spokesman. The six comprised two men and four women.

Safety orders from 2008 not obeyed at Hong Kong building where fire erupted

One of the five killed was a 23-year-old Indonesian man who was suspected to have fallen out of the window from his fourth-floor flat in an attempt to escape the blaze, according to another source. The man held a Hong Kong identity card.

The source said the three victims found in the second-floor public corridor included Tsang Hing-wai, 70, and an unidentified woman. The third was a 24-year-old Indonesian woman who was also the holder of a Hong Kong identity card and lived in a fourth-floor flat.

Tsang, who had emigrated overseas from Hong Kong, was believed to have been staying in one of the building’s guest houses after he returned to the city.

“We are still investigating why they were there,” the second source said, adding that they might have tried to run downstairs but were forced to retreat because of dense smoke.

The fifth victim, who was found unconscious on a staircase between the seventh and eighth floors, was Lai Ka-lun, 67, a Hong Kong resident. Officers were still trying to establish where he lived in the building.

The source said autopsies would be carried out to establish the cause of their deaths.

Safety orders from 2008 not obeyed at Hong Kong building where fire erupted

The Fire Services Department has set up a task force headed by a senior divisional officer to investigate the cause of the blaze and the reasons behind the multiple casualties.

Police appealed for witnesses and anyone with information to contact officers on 3661 8386.

The Jockey Club said it would offer more than HK$2.5 million (US$319,140) in financial help to the affected through the Social Welfare Department.

It will extend HK$150,000 to the families of each individual who died. Those who sustained serious injuries will each receive HK$100,000, while individuals with injuries but in stable condition will each be given HK$50,000.

The fire broke out shortly before 8am on Wednesday, when many of the building’s 300 tenants were still sleeping. Some of the residents said the dense smoke made their escape difficult and they had to wait for more than an hour before they were rescued.

Thirty-five fire engines and 24 ambulances were sent to the scene after authorities received a call at 7.53am. More than 210 firefighters and paramedics were deployed.

The fire was brought under control about an hour after it was reported and was largely put out by 10.30am.

According to the fire department, about 250 people were evacuated from the building and another 50 residents had fled before emergency personnel arrived.

The New Lucky House blaze is one of the city’s deadliest fires in recent years.

In November 2020, a fire tore through an 800 sq ft flat converted into an unlicensed restaurant on the first floor of a single-staircase building on Canton Road in Yau Ma Tei, leaving four men and four women, aged eight to 40, dead.

The deadly blaze prompted authorities to carry out inspections at more than 2,500 old buildings across the city.