Firefighters are still searching for hundreds of missing people after a massive fire tore through multiple high-rise residential buildings in Hong Kong.

At least 65 people died in the blaze - the city's deadliest in more than 70 years - at Wang Fuk Court's complex, which is home to thousands.

The tower blocks had been undergoing extensive renovations - and while the exact cause for the fire is unclear, police say materials on the outside of the buildings may have facilitated its spread.

Three construction company executives have been arrested on suspicion of manslaughter and gross negligence, and Hong Kong's chief executive John Lee has vowed to launch a comprehensive investigation.

The fire, which tore through seven of eight tower blocks in Tai Po district on Wednesday, is now basically under control, Lee said.

It started at 14:51 local time (06:51 GMT) on Wednesday, with flames and thick clouds of grey smoke seen billowing from the towers, dominating the city's skyline.

By 18:22 local time, officials upgraded the fire to a level five - the most serious category.

Firefighter Ho Wai-ho, 37, was among those killed in the blaze. He was found collapsed at the scene about 30 minutes after contact with him was lost.

Ten other firefighters are also injured, the fire department said.

The fierce heat of the blaze, as well as dangerous debris and the risk posed from collapsing scaffolding, has hampered rescue efforts, but the fire department has so far rescued 55 people.

More than 270 people remain unaccounted for, while 70 people are injured.

The mood in Hong Kong has shifted from shock to anguish, as questions grow regarding who should be held accountable for the blaze.

Residents raised concerns on social media, revealing that several did not hear a fire alarm when the fire broke out.

Reports of their complaints regarding high renovation fees and potential fire-safety regulation violations have surfaced widely online.

Authorities are now determining the implications of such negligence and safety lapses, with a focus on reevaluating fire safety and construction materials used in high-rises.

President Xi Jinping has also expressed sympathy and urged efforts to minimize losses following this devastating event.