Police said those wounded were two assailants and the man being attacked, and that all three were of "South Asian" origin.
"Five to six...men, with some carrying knives, were attacking another man," police officer Ma Wai-hing told reporters at the scene of the incident in the city's commercial district of Yau Ma Tei.
No further details were given about the attack.
"After verbal warnings were ignored, four shots were fired. Two men were shot," he said. The pair were arrested and hospitalised with wounds to the forearm and waist. They, along with the knife attack victim, are in a stable condition, Ma said.
Police said four shots were fired as the first shot was "ineffective" in stopping the attack.
An AFP reporter at the scene said a road intersection was cordoned off around noon, with detectives gathering evidence and two fillet knives lying on the ground.