HONG KONG, Nov. 27 -- Investigators are examining several possible factors behind the rapid spread of the five-alarm blaze that tore through Wang Fuk Court in Tai Po, with scrutiny falling on the fire resistance of scaffolding, the use of highly flammable foam boards, wind-carried burning debris and alleged smoking by renovation workers.

Fire engineers told the South China Morning Post that the scale of the inferno suggested weaknesses in multiple areas, from the materials used on bamboo scaffolding to fire safety management at the extensive renovation works across the eight 31-storey blocks.

Flaming debris blown by the wind was also cited as a possible factor, while some residents said they had repeatedly seen workers smoking at the si...