Two men died and more than 30 people were evacuated after a fire broke out at a building in Wan Chai in the early hours of Thursday.
Police have classified the case as murder, arson and suicide.
Firefighters were called to Kam Lok Mansion in Lockhart Road at about 3am, and it took them more than an hour to put the blaze out.
At a press briefing, police superintendent Sin Kwok-ming said one of the dead was an 89-year-old man surnamed Lau who had lived in a flat there for over three decades.
His body was charred and there was a two-centimetre wound on his chest apparently caused by a sharp object, Sin said.
The man was declared dead at the scene.
The other man, 53, suffered serious burns and was declared dead after he was rushed to Ruttonjee Hospital. He also had a one-centimetre wound on his chest.
Police believe the two men had a dispute. They said the 53-year-old man attacked the elderly man with a knife and might have set fire to the unit.
Sin said two cans of inflammable solvent were found and were being sent to a laboratory for further tests.
Last updated: 2022-12-01 HKT 22:43