“I only have four or five masks left at home, there’s nothing to buy even if I wanted to,” the Leung, 81, said.

“This is worse than Sars in 2003,” he said, referring to an outbreak of the respiratory disease that infected more than 8,000 people in Hong Kong.

“I don’t know where all the masks have gone this time.”

As of Friday afternoon, 24 patients have been diagnosed with the virus, which originated in the city of Wuhan in central China.

Despite reassurances from Chief Executive Carrie Lam Cheng Yuet-ngor that the government was working on securing fresh supplies of face masks, some elderly residents said they could not rely on authorities any more.

“I have waited an hour with my father, of course we are worried, the government can do nothing,” a man in his 60s said.

It was not an uncommon refrain.

“The government can do nothing, there are no masks anywhere in the world,” a 66-year-old woman who did not arrive in time for the giveaway said.

The woman said she reused her masks for two to three days at a time and had only about six left at home.

One retiree, surnamed Yeung, said she arrived 15 minutes after the queue started moving at 1pm, but it was already too late.

“My daughter called me after she saw the online post so I rushed here,” the 69-year-old said, adding she had about three face masks left at home. “I can’t buy it even if I have money.”

The last-minute giveaway came as a surprise to facility management at Oi Tung Shopping Centre, where a Circle K shop is located.

A security guard who helped oversee the queue, said they received notice of the giveaway at about noon, the same time the Facebook post went up.

While three police vans were parked on the side of the road, he said “people here have been quite calm so far”.

At a Circle K shop in So Uk estate in Kowloon’s Sham Shui Po neighbourhood, meanwhile, an employee told the Post that elderly residents began queuing in front of the store just after the midday announcement. Within two hours, the masks were gone, the employee said.

“We said there would be 1,000 vouchers available, but there were certainly more people in line than that,” said the employee.

In an emailed statement, Circle K said the giveaway was announced at the last minute to make sure elderly residents did not queue for too long. The 100,000 masks were sourced from a number of countries, including Japan, it said.

“If we can successfully source more masks, we want to contribute more,” the company said. “We would also like to call on other companies to do it too.”

Separately, Hong Kong Television Network (HKTV), a media company turned e-commerce platform, announced on Friday it had purchased a mask-making machine from a Taiwanese manufacturer for US$200,000 (HK$1,552,530) earlier this week.

“We will have the machine in one month, and we will produce face masks ourselves,” the company wrote in a Facebook post, pointing out that it had sold 4.5 million masks to customers since January.

HKTV did not say how many masks the company would produce or when the masks would be available.

Additional reporting by Zoe Low