The woman is believed to be a resident on the first floor of the Kwan Yue Elder Nursing Home in Yuen Long. The building faces On Lok Road, where tear gas was fired by riot police against protesters.

On Sunday, a staff member from the nursing home said no residents had been sent to hospital because of the tear gas. He said police had called them in advance to take precautionary measures against possible chaos.

An estimated hundreds of thousands of Hongkongers had defied a police ban on Saturday to march in the northern town to protest the brutal violence in Yuen Long MTR station last week, where a mob indiscriminately attacked passengers and protesters returning from a march against the extradition bill.

On Saturday afternoon, protesters advanced along On Lok Road with their umbrellas up as they hurled objects at the police, who used tear gas, sponge grenades, pepper spray and batons to drive them back at multiple spots.

Senior Superintendent Yolanda Yu Hoi-kwan had earlier said no elderly care homes had been affected, and said the force had called 22 of them nearby on Saturday. Staff from two other nursing homes confirmed they had received such calls, and added they were not affected with the windows closed.

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Yuen Long was largely back to normal on Sunday morning, as businesses reopened and shoppers returned to the streets.

Chinese pastry store Hang Heung bakery, which is famous for its “wife cakes”, said business on Saturday had been better than usual.

Some protesters had tried to get around the banned march by saying they were only going to Yuen Long for the store’s traditional pastries.

“All the products were sold out, so we had to close earlier in the evening,” a staff member said.

But along On Lok Road, which was closer to the clashes, small businesses suffered from a drop in profits.

Apple Wong, a manager of a cafe, said the restaurant had closed earlier than normal as the protest broke out.

“We usually earn between HK$5,000 and HK$6,000 a day, but we only had around $1,000 yesterday,” she said.

Traces of the protest could be found throughout the northern town, with graffiti of the slogan “liberate Hong Kong; revolution of our times” spray-painted on the walls of bridges and alleyways.

The phrase was the election slogan of pro-independence activist Edward Leung Tin-kei in 2016, who was subsequently barred from legislature elections and jailed for six years for his role in the Mong Kok riot, which took place in the same year.

Metal railings along On Lok Road had gone missing after protesters removed them to form barricades, while certain parts of the ground had been dug up, and bricks were missing.

Some residents recounted their experiences of Saturday’s chaos.

Cheryl Yuen, a resident living in a building on Tai Cheung Street, said she had stayed at home for the whole day, but could smell the tear gas even in her home on the 11th floor.

“We could smell the gas and it was irritating our eyes. We immediately closed the windows and turned on the air con,” she said.

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A 35-year-old resident, who only gave her name as Mable, said she was stung by tear gas when she went to buy food on Saturday. “From where I was standing, I did not notice the police putting up warnings,” she said.

Joyce Leung, a resident who lives on Shui Che Kwun Lane, said the impact of tear gas was limited as she thought all staff of the nursing homes nearby had prepared well and closed all the windows in advance.

But Cyrus Wong Ka-ho, who owns an interior design business on the same lane, criticised the police’s arrangement.

“It was not necessary to use tear gas and deploy the riot police,” the 30-year-old said. “Most protesters were peaceful and polite at first and the area is close to residential area and elderly homes after all.”

Lawmaker Claudia Mo Man-ching, convenor of the pro-democracy camp, agreed as she lashed out at the decision to fire tear gas in crowded neighbourhoods where nursing homes are located.

“The aggressiveness of the police force has become almost out of control and unchecked,” she said.