Firefighters said the blaze broke out at around 2.30am in a 12th floor flat at Pak Tin Estate.
The man who died suffered multiple fractures after falling from the building. Police said they believed he had been trying to escape thick plumes of smoke.
Another woman was unconscious by the time she was rescued, with the other injuries mostly down to smoke inhalation.
“People were very frightened, screaming, saying there’s a fire. It was so raucous,” a resident said.
“Neighbours living on that floor told me the whole corridor was dark, they couldn’t see anything and had to hold on to the wall to escape. Luckily they’re fine,” he added.
An assistant district commander for crime in Sham Shui Po, Lui Che-ho, said preliminary investigations suggested someone started the fire following a dispute.
“In the course of our investigation, there is information suggesting that someone has left or thrown a cigarette end inside the premises and that has led to the big fire,” he said.
“But we’re still exploring why the fire… eventually turned into such a disaster.”
About 600 people were evacuated due to the blaze, which was put out by firefighters after around 30 minutes.
Last updated: 2021-09-10 HKT 13:26