The victim was targeted when he left his vehicle at a car park outside King Kung House at Choi Wan (II) Estate in the Choi Hung area of Wong Tai Sin district at about 12.56am on Monday.
“Two knifemen suddenly turned up and slashed the victim in the head, forearms and back before fleeing in an Audi car,” the source said.
The injured man was rushed to United Christian Hospital in Kwun Tong for treatment.
Officers mounted a search, but no arrests were made.
About half an hour later, a blazing car believed to have been used in the attack was found near the Hong Kong University of Science and Technology at the junction of University Road and Clear Water Bay Road in Sai Kung. It was about 7.5km (4.7 miles) away from the site of the knife attack.
Firefighters extinguished the blaze and no one was injured in the fire.
Detectives from the Wong Tai Sin criminal investigation unit said they checked surveillance camera footage to gather evidence.
Police handled 2,334 reports of triad-related crimes last year, down 8.6 per cent from 2,554 cases logged in 2022.
Last month, officers from Hong Kong Island regional anti-triad squad arrested 142 people in an 11-day crackdown on triad-controlled drug, sex and gambling businesses.
During the operation that ended on April 30, police raided and shut down 18 vice establishments, seven gambling dens and an unlicensed pub.
The force said the suspects included alleged triad members, gamblers and those who purportedly ran the 26 illegal premises on Hong Kong Island.