Three construction company executives, consisting of two directors and an engineering consultant, have been arrested for alleged manslaughter following a deadly fire outbreak that killed 83 people in Tai Po, Hong Kong.

Police said the fire at a housing estate on Wednesday could have been caused by “gross negligence” by the construction firm.

“We have reason to believe that the company’s responsible parties were grossly negligent, which led to this accident and caused the fire to spread uncontrollably, resulting in major casualties,” Police Superintendent Eileen Chung said without mentioning the company’s name.

According to the South China Morning Post, the local fire department disclosed that at least 83 people died in the fire, with 40 of the 70 injured declared to be in critical condition in the hospital.

With 270 others declared missing, rescuers, among whom 11 were also reported injured, have evacuated hundreds of residents who are now among about 900 placed in temporary shelters, as volunteers continue to bring supplies to the displaced.

The fire outbreak was said to have started on the external scaffolding of a 32-storey tower, then spread into the building and to seven of the eight structures. It was still raging as of Thursday morning.

It was said to have raised bamboo scaffolding outside several flats of the building, with burning sections of green scaffolding mesh falling to the ground. The complex, built in the 1980s, had been under renovation for a year before the blaze.

Deputy director of Fire Service operations, Derek Armstrong Chan, said, “Debris and scaffolding of the affected buildings are falling down. The temperature inside the buildings concerned is very high. It’s difficult for us to enter the building and go upstairs to conduct firefighting and rescue operations.”

The police say they are investigating the renovation of the complex to determine whether the materials, which included mesh and plastic sheets, used for the exterior of the high-rise buildings complied with fire resistance standards.

According to the Director of Fire Services, Andy Yeung, officers found highly flammable foam sheets, which they suspect caused the unusually rapid spread of the fire.

The inferno, which was initially classified as a “No 1” alarm fire before spreading to the other buildings, worsened with dark smoke spreading to the sky at Wang Fuk Court and was quickly raised to “No 4” classification before it was further raised to the highest level, “No 5,” within hours.

The country’s chief executive, John Lee Ka-chiu, in a press conference at Prince of Wales Hospital in Sha Tin on Thursday, after visiting a community hall, disclosed that the blaze is now “basically under control.”

The inferno is said to be the deadliest recorded in years, after the 20-hour level five outbreak of November 1996, which witnessed 41 deaths in a building in Kowloon.