Hong Kong police officers rarely fire their guns, but when they do, it grips the city’s attention. On Thursday, officers shot dead a man who had taken a woman hostage while brandishing a 30cm knife at a shopping centre in Tuen Mun. Under police guidelines, officers may open fire to protect anyone – including themselves – from death or serious injury. They may also use lethal force against anyone believed to have committed a serious or violent crime and who is attempting to evade arrest. Firearms...