Inaccessible rear staircases have been identified as the main reason for the high death toll in the Mong Kok inferno that claimed nine lives last November.
Seven of the 12 flats in two adjoining eight-storey buildings in Fa Yuen Street had their rear staircases blocked after the flats had been illegally subdivided into self-contained rooms, according to a government source.
"The exit to the rear staircase in these flats was blocked by one of the subdivided rooms and only occupants of the room could use it," the source said. "Other tenants were unable to access the exits and had to escape through the front door, but were caught by choking fumes that filled the front staircase.
"They inhaled smoke and passed out on the staircase. Some tried to run to the roof but were unable to make it."
A woman, who ran with her boyfriend in an effort to escape Hong Kong's deadliest fire in 15 years, was found dead near an exit to a roof. Her boyfriend survived but was in intensive care in hospital for days.
The source said results of postmortem examinations showed the nine victims, all found in the front staircase, died from suffocation.