Police chief Raymond Siu on Thursday said an officer who shot dead a man who allegedly charged at officers while brandishing scissors and a chopper exercised professional judgement to prevent others from being injured.

The fatal shooting came as officers responded to reports of domestic violence at a flat in North Point on Sunday night.

Calling the case "an unfortunate incident", Siu said the force was saddened by the death of the man, 38, and wanted to offer its condolences to his family.

He said the man was 1.5 metres away and officers had to make a split-second decision as to how to react.

"For the use of force or other firearms, basically we have strict enforcement guidelines governing our officers, under what sort of circumstances can they use their firearms," the police commissioner said after attending a district council meeting.

"Our initial enquiries and review indicate that our officers at the scene have exercised professional judgement with a view to preventing any other person, including the officers themselves or other members of the public, from being seriously injured."

Siu said the force is "cautiously" investigating the incident.