A devastating fire has torn through several high-rise apartment blocks in a Hong Kong housing complex, killing at least 44 people and leaving hundreds of people missing, CNN reported, citing an official statement.
Firefighters have been struggling to reach residents stranded on upper floors as the blaze continues to rage.
Authorities revealed early Thursday that three men have been arrested in connection with the incident -- two directors and a consultant from a construction company.
Police accused them of "gross negligence" after investigators discovered the company's name on highly flammable polystyrene boards found blocking windows in some apartments, according to CNN.
Officials also suspect that other construction materials at the site -- such as protective nets, canvas sheets, and plastic coverings -- did not meet required safety standards.
Seven of the eight towers in the complex, which houses many elderly residents, were still burning hours after the fire first broke out.
The fire is now believed to be Hong Kong's deadliest in nearly 30 years, surpassing even the infamous 1996 Garley Building blaze that killed 41 people.
The inferno, centred in the Tai Po district, has been burning for roughly 16 hours, with firefighters focusing their efforts on three of the worst-affected towers. They say the flames in four other buildings have been brought "under control," though not fully extinguished.
Questions are mounting about how the fire spread so quickly. Andy Yeung, Director of Fire Services, said crews noticed polystyrene boards blocking windows in multiple units, a detail he called highly unusual, as per CNN.
"These polystyrene boards are extremely inflammable, and the fire spread very rapidly," he said.
"Their presence was unusual, so we have referred the incident to the police for further enquiries," Yeung added.
Hong Kong Chief Executive John Lee said the city's housing authorities will also examine whether the protective layers coating the buildings during refurbishment were sufficiently fire-resistant.
"We will hold those accountable in accordance with the laws and regulations," he said.
Officials are also looking at the role of bamboo scaffolding, commonly used to wrap Hong Kong buildings during construction or repair work, which has previously been cited as a factor in the spread of fires.