Police say they suspect a shooting and machete attack in Central in the early hours of Friday was linked to a dispute between two triad gangs.
The attack took place on Wyndham Street near Lan Kwai Fong, with at least eight men armed with machetes launching an attack on people inside three vehicles.
One of the vehicles drove off and hit the attackers, police said, and shortly afterwards at least two shots were fired.
When officers arrived they found six people at the scene. Three of them were injured, one with a gunshot wound to the abdomen. Another had head injuries and the third wounded person had a leg injury.
Four people, aged between 23 and 42, have been arrested on suspicion of attempted wounding and possession of offensive weapons.
"The incident was instigated by two triad groups. They have been at each other's throats for quite some time," said senior superintendent Ho Chun-tung from the Organised Crime and Triad Bureau.
"The dispute is mostly caused by illegal activities such as illegal gambling, transactions of trafficking dangerous drugs and things like that. This is kind of a retaliation between these two triad groups," he claimed.
Officers recovered nine machetes and found two bullet casings at the scene.
Ho said locating the gun used – thought to be a semi-automatic pistol – is now their priority.
He added that people should not be too worried about the shooting.
"I don't think an isolated incident should cause a great alarm to the general public that there's a gun problem in Hong Kong. But having said that, the police are very very concerned about the case with a real firearm being used and someone being hurt, especially in a crowded area like Central."