HONG KONG (AP) — Firefighters battled a blaze at a high-rise apartment complex in Hong Kong for the second day on Thursday, as the death toll rose to 75 in one of the deadliest blazes in the city's modern history.

Rescuers holding flashlights were going from apartment to apartment at the charred towers as thick smoke continued to pour out from some windows at the Wang Fuk Court complex, a dense cluster of buildings housing thousands of people in Tai Po district, a northern suburb near Hong Kong’s border with the mainland.

It was unclear how many people were missing or trapped. Hong Kong leader John Lee said contact had been lost with 279 people early Thursday. Authorities did not provide updates on the missing people or how many were still inside the ravaged buildings Thursday during a press conference.

Latest video showed rescuers searching in some apartments in the dark. Orange flames were still seen from inside several windows, though the whole complex was now largely a blackened ruin.

Firefighters have been trying to control the flames since midafternoon Wednesday, when the fire was believed to have started in bamboo scaffolding and construction netting and then spread across seven of the complex’s eight buildings. Fires in four buildings had been effectively put out, with the remaining three towers under control, authorities said Thursday afternoon.

Rescuers are “battling high temperatures and carefully going up floor by floor, thoroughly searching and aiming to rescue people as quickly as possible,” said Wong Ka-wing, deputy director of the fire services. “(We) don’t rule out rescuing more injured people.”

More than 70 people were injured, including 11 firefighters, the Fire Services Department said. About 900 people were evacuated to temporary shelters overnight.

Resident Lawrence Lee was waiting for news about his wife, who he believed was still trapped in their apartment.

“When the fire started, I told her on the phone to escape. But once she left the flat, the corridor and stairs were all filled with smoke and it was all dark, so she had no choice but to go back to the flat,” he said, as he waited in one of the shelters overnight.

Winter and Sandy Chung, who lived in one of the towers, said they saw sparks fly around as they evacuated Wednesday afternoon. Although they were safe, they were worried about their home. “I couldn’t sleep the entire night,” Winter Chung, 75, told The Associated Press on Thursday.

Three arrested on suspicion of manslaughter

Three men, the directors and an engineering consultant of a construction company, were arrested on suspicion of manslaughter. Police have not directly named the company where they work.

"We have reason to believe that those in charge of the construction company were grossly negligent,” said Eileen Chung, a senior superintendent of police.

Police on Thursday also searched the office of Prestige Construction & Engineering Company, which the AP confirmed was in charge of renovations in the tower complex. Police seized boxes of documents as evidence, according to local media. Phones for Prestige rang unanswered.

Authorities suspected some materials on the exterior walls of the high-rise buildings did not meet fire resistance standards, allowing the unusually fast spread of the fire.

Police also said they found Styrofoam -- which is highly flammable -- attached to the windows on each floor near the elevator lobby of the one unaffected tower. It was believed to have been installed by the construction company but the purpose was not clear. Secretary for Security Chris Tang said they would investigate the materials further.

Buildings were covered in scaffolding

The housing complex consisted of eight buildings with almost 2,000 apartments for about 4,800 residents, including many older people. It was built in the 1980s and had been undergoing a major renovation. Hong Kong's anti-corruption agency said on Thursday it was launching a probe into possible corruption relating to the renovation project.

Officials said the fire started on the external scaffolding of a 32-story tower, then spread on the bamboo scaffolding and construction netting to the inside of the building and then to the other buildings, likely aided by windy conditions.

Bamboo scaffolding is a common sight in Hong Kong at building construction and renovation projects, though Lee said officials will meet with industry representatives to discuss a switch to metal scaffolding amid safety concerns.

“While we know that bamboo scaffolding has a long history in Hong Kong, its flame retardancy is inferior to that of metal scaffolding. For safety reasons, the government believes that a complete switch to metal scaffolding should be implemented in suitable working environments,” said Eric Chan, the Chief Secretary for Administration.

Authorities will also be carrying out immediate inspections of all housing estates that are undergoing major renovation work to ensure scaffolding and construction materials meet safety standards.

The fire was the deadliest in Hong Kong in decades. In November 1996, 41 people died in a commercial building in Kowloon in a fire that lasted for around 20 hours.

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Wu reported from Bangkok. Researcher Shihuan Chen in Beijing contributed to this report.