“After having dinner with three other friends, the two victims were walking along Shanghai Street when three knifemen jumped out from a car and attacked them,” the insider said.

The attackers then returned to their car and sped off towards Dundas Street, he added.

The source said the 66-year-old man suffered knife wounds to his left ear, neck, chest, left forearm and two shoulders, while the mainlander was slashed on the left side of his face, an arm and a knee.

According to the force, the two victims were conscious after the attack, and their friends took them to Kwong Wah Hospital in Yau Ma Tei.

Police have mounted a search and set up roadblocks in various locations, but no arrests have been made so far.

Officers from the Mong Kok anti-triad squad are investigating.

The source said detectives were poring over surveillance camera footage in an effort to identify the suspects and their escape route.

In March, authorities installed 15 sets of surveillance cameras in Mong Kok as part of a broader plan to have 2,000 set up by the end of 2024, with a focus on densely populated zones and high-crime areas.

The city recorded 4,237 cases of violent crime between January and May of 2024, up 9.4 per cent from 3,872 reports over the same period last year.

Reports of triad-related crimes rose by 6.2 per cent to 787 in the first five months of this year from 741 cases logged in the same period in 2023.