An internal inquiry will examine why two police officers gunned down a 21-year-old man who was threatening his estranged wife and others with a paper cutter - the first fatal shooting by officers in two years.
The city's security chief has promised a thorough investigation of the killing of delivery worker Ho Sai-tung and says police guidelines allow the use of firearms only to prevent "severe crime".
Police said Ho was holding a security guard at knifepoint and was about to attack his wife and a policewoman when two officers shot him at Hong Nga Court, in Lam Tin.
A police source said the man, said to have been extremely agitated, ignored repeated warnings from officers before he was shot at three times from a distance of approximately one metre.
"The man suffered gunshot wounds and fell onto his wife and the policewoman," the source said. "An initial examination showed two of the shots hit his forehead and neck."
Ho was pronounced dead at the scene.
Secretary for Security Lai Tung-kwok said police were concerned about the case and that the findings of its investigation would be submitted to the coroner for an inquest.
The police force had very strict rules on the use of firearms, he said. "According to police guidelines, the use of firearms is to stop severe crime from happening," he said.
Asked whether it had been necessary to fire three shots at the man, the police source said that question would form part of the internal investigation. But initial investigations had shown that "the two officers were justified in opening fire as the lives of the two women were in danger". It is understood an initial report will be submitted to police management within 48 hours.
Yesterday's drama began when Ho went looking for his 21-year-old wife, who had left their home in Sau Mau Ping the previous day with the couple's seven-month-old son after a heated argument.
She accused Ho of having an affair, police said.
The woman and child stayed the night at a friend's flat in Heng Nga House, Hong Nga Court, in Lam Tin. When Ho arrived at the building to look for his wife and son, he argued with a 48-year-old security guard who stopped him at the ground-floor lift lobby.
Other security guards called the police, and when officers arrived at the scene, a tense stand-off ensued as Ho held a paper cutter to the guard's throat. Matters took a turn for the worse when Ho's wife walked out of the lift.
"Upon seeing his wife, Ho became very emotional and agitated," said Senior Superintendent Eugene Yue, head of the Kowloon East regional crime unit.
Ho then left the guard and rushed towards his wife in an apparent attempt to injure her, Yue said. As a policewoman pulled the wife back to protect her, both women lost their balance and fell to the ground.
"Ho was standing over them and about to do something to hurt them," Yue said, adding that the man was still holding the knife at the time. "As repeated warnings were ignored, two officers fired a total of three shots."
A colleague of the guard held at knifepoint said: "Police ordered the man to drop the weapon and not to be emotional. The officers shouted repeatedly before there were loud bangs."
A resident who lives two blocks away said she heard three loud shots. "I heard bang, bang, bang and I initially thought it was thunder," she said. "Then I heard ambulance or police sirens."
Neither the security guard nor Ho's wife were injured.
Yue said a constable and a station sergeant fired the shots. Officers have retrieved CCTV footage of the scene. An autopsy will be conducted on Friday.
In March, a police officer fired two shots as he chased three suspected illegal immigrants who hurled stones at him in Shek O. No one was injured. In May 2012, a traffic policeman shot dead a 36-year-old man involved in a suspected triad attack in Sham Shui Po.