Despite all his training at police school, Sergeant Ko Wing-cheung could never have envisaged the epidemic that brought Hong Kong to a standstill in 2003.
All eyes had been on the invasion of Saddam Hussein's Iraq, then suddenly the world's media turned its attention to Kowloon Bay - the epicentre of the severe acute respiratory syndrome (Sars) outbreak a decade ago.
The city reacted with fear. No one knew much about the silent killer or why the residents at Amoy Gardens, where the outbreak began, were particularly vulnerable to it. As Hong Kong's streets fell silent, Ko and his colleagues across the emergency services swung into action. Some on the front line would die.
When the authorities got to work on the Kowloon Bay estate, 42 of 329 residents infected had already died. In total, 1,755 people across Hong Kong contracted the virus, among whom 299 died.
Police officers tasked with assisting quarantine efforts and other efforts to combat Sars were just doing their job, Ko says, as the disease, and fear of it, became rampant.
"With Sars … the biggest challenge [was that] we didn't know what to expect," he says. "There was nothing we could foresee."
Ko, 44, said he joined the police force because he wanted to help others. He got his chance when he was assigned to assist the residents of Amoy Gardens. But it cost him dear: Ko contracted Sars after working on the estate. Yet he defied the doctors who expected him to die. He has now been in the police force for 20 years, despite bearing the impact of the disease on his health.
His lung capacity has dropped 22 per cent. His wife, who was also stricken, even now has problems with both her heart and legs.
As they carried out the hard work of sealing off Amoy Gardens, Ko and his colleagues were the friendly face of the force. When they initially visited families on the estate - who were undoubtedly terrified by what was going on - Ko and his fellow officers made get-well cards for each family to try to build trust with the residents.
Aware that he was risking his life, his health and that of his wife and two boys, Ko offered to stay away from the family home until the outbreak was under control.
"I discussed it with my wife and said: 'Why don't I sleep at the [police] base during this time because it is really quite dangerous'," he explains. "I was definitely worried.
"At that time, my wife was very supportive and said: 'As long as you're careful, it's OK'. During Sars, we didn't know where the light at the end of the tunnel was."
Ko fell ill 10 days after being posted to Amoy Gardens, despite the layers of protection for quarantine workers.
He spent weeks in hospital and some time in intensive care.
Ko's heroes are the doctors who treated him when he was at his worst, including "Sars hero" Professor Joseph Sung Jao-yiu, now vice chancellor of Chinese University, and his police colleagues, who rallied round his family as his wife and youngest son were also struck down by the disease.
"When I got Sars and was in the hospital, my wife, kids and family were isolated. I really relied on my colleagues to help out. They would deliver groceries, cleaning supplies and masks."
That went on until his wife and youngest son, then aged two, were admitted to hospital. Remarkably, his grandmother and nine-year-old son, who shared the same home, did not contract the disease.
At one point, all the members of his family were separated. His wife and two-year-old son were both receiving treatment in different parts of Tuen Mun Hospital, making a psychological recovery more difficult.
"It was heartbreaking not seeing my family," Ko says. "I do this job because of a will to protect people's lives and assets, to guard other people's safety. You work really hard to protect others, but then you can't even protect your family."
Ko made a recovery within two months of leaving hospital.
He insists he's not a hero, even though he could easily have died helping protect others. A decade later, he's still doing it, out on patrol where he feels he belongs.