The death toll from Hong Kong’s worst fire in its peacetime history has risen to at least 55, authorities say, with hundreds of others still unaccounted for.

Hong Kong’s Fire Services Department confirmed the updated death toll on Thursday, a day after flames tore through an eight-building apartment estate in the northern part of the Chinese city.

Fire officials told a news conference that 51 of the victims died at the scene, while four succumbed to their injuries in hospital.

At least 268 people are still unaccounted for after the blaze at the Wang Fuk Court estate in Tai Po, according to authorities.

Firefighters worked into the night to quench the fire that broke out on Wednesday afternoon, as thick, black smoke billowed from the 31-storey towers and orange flames lit up the sky.

Derek Armstrong Chan, deputy director of fire services, earlier told reporters that darkness overnight had hampered their operations, and firefighters were still having difficulty accessing two of the buildings.

“Up to this moment, the temperature inside the fire scene is still very high,” Chan told reporters.

Chan on Wednesday said firefighters had struggled to respond to residents’ pleas for help, with falling debris and scaffolding posing a danger to front-line personnel.

Local media reported that some residents were believed to be trapped inside their homes.

Police said they arrested three men on suspicion of manslaughter in connection with the fire, without providing details of their alleged wrongdoing.

The blaze is Hong Kong’s deadliest since World War II, when Japanese forces occupied the then British-ruled territory.