At approximately 10:05 p.m. on July 1, 2021 — the 24th anniversary of Hong Kong's return to Chinese sovereignty, a public holiday — Leung Kin-fai, 50 years old, approached a police officer near East Point Road in Causeway Bay and stabbed him. The officer fell. Three nearby colleagues drew their guns. Leung then turned a knife on himself and inflicted fatal wounds; he died at the scene. Police Commissioner Raymond Siu came to the scene personally. By 11:20 p.m., a woman had been stopped nearby carrying a utility knife and arrested; a man was taken away with his head covered. Police found a fruit knife and a sabre at the scene. They classified it as attempted murder and suicide. The government characterized it as terrorism.

Leung Kin-fai had no criminal record. He worked in the purchasing department of Vitasoy International and had briefly worked as an information officer at Apple Daily in 2008. He lived with his parents in San Po Kong. When police searched his belongings they found newspaper clippings, pamphlets from the 2019 protest movement, and a USB drive containing multiple suicide notes. The notes described his hatred of police, whom he accused of 'sheltering criminals' and committing 'atrocities' that the system could not check. He had chosen July 1 deliberately — the anniversary — and had settled his financial affairs in advance. Security Secretary Chris Tang said publicly that Leung had been 'radicalised,' citing material found on his computer, though he offered no further specifics. A psychology professor at a Hong Kong university, speaking to CNN, warned against simple explanations: Leung, he said, was one expression of a city that had never collectively processed what its people experienced in 2019.

In the days that followed, some Hong Kongers went to East Point Road with white chrysanthemums. The gesture — flowers at the site of a death — is ordinary across many cultures, and in Chinese tradition the seventh day after a death carries particular significance. Police responded to it as a security matter. Officers stopped and searched people carrying flowers. Littering tickets were issued to those who placed them. A secondary school student said he had been stopped four times in one day and asked 'Has someone died in your family?' before being let go, only to be stopped again. 'Grandma Wong' — Alexandra Wong, well-known from the 2019 protests — came to the site with flowers and was immediately surrounded by officers. Police warned that encouraging memorial activities was 'no different from supporting terrorism.' Four university student leaders who passed a union motion mourning Leung's death were arrested in August under the national security law and sentenced to two years each, later reduced on appeal to fifteen months.

The stabbing was one act by one man, but it arrived in a city where the ordinary channels for processing collective grief and political disagreement had, by mid-2021, largely closed. The annual July 1 marches that once drew hundreds of thousands had not taken place since 2020. Victoria Park, their traditional starting point, had been enclosed by police that day. Thousands of people had emigrated. The national security law had been in force for a year. In this context, the question of how to mourn — or whether mourning the attacker was itself a political act — became the argument. Chief Executive Carrie Lam cited the stabbing as a reason she would not hold town hall meetings. The reporter who filmed the attack live was visited at her home by police, had her residence searched, and had her travel documents confiscated. Paul Yip Siu-fai, director of the Centre for Suicide Research and Prevention at the University of Hong Kong, said the attack 'rang a warning bell' — not because it portended more violence, but because it revealed how inadequate the available responses had become for people in profound distress.