Hong Kong closed schools and cancelled hundreds of flights on Tuesday as Super Typhoon Ragasa swept across the South China Sea, with authorities warning of one of the most destructive storms to hit the city in recent years.

The storm was packing maximum sustained winds of 220 kilometres (137 miles) per hour near its centre, according to the Hong Kong Observatory, which issued its third-highest typhoon warning signal, T8, at 2:20 pm (0620 GMT).

“The weather is expected to start deteriorating rapidly later today, with winds strengthening quickly,” the observatory said, warning that storm surges could push water levels up to four metres by Wednesday morning.

Officials compared Ragasa’s potential impact to the devastating typhoons of 2017 and 2018, which caused hundreds of millions of dollars in damage.

In the coastal neighbourhood of Lei Yue Mun, 71-year-old Yang Lee-o said workers had already placed sandbags to prepare for flooding. “Lei Yue Mun is the hardest hit whenever there’s a typhoon or rainstorm,” she said, recalling that water once rose to her thighs during a past super typhoon.

The storm had already wreaked havoc in the northern Philippines, where landslides killed at least two people, trees were uprooted, and thousands of residents took shelter in schools and evacuation centres.

Across southern China, authorities ordered shutdowns in at least 10 cities, including Shenzhen, which evacuated 400,000 people. The city’s emergency management bureau warned residents to stay indoors except for emergency personnel and essential workers. Other cities enforcing similar measures included Chaozhou, Zhuhai, Dongguan and Foshan.

In Hong Kong, the storm forced the cancellation of more than 500 Cathay Pacific flights, with airport authorities warning of “significant disruption” to flight operations from Tuesday evening through Wednesday.

Travellers scrambled to rearrange their plans. “We had to book a new hotel here, which also costs us some money so we are kind of really disappointed,” said 24-year-old student Lilly Rober, whose flight to Japan was postponed.

Thousands of workers rushed home after the T8 signal was raised, with bus operators announcing reduced services. Classes were suspended for Tuesday and Wednesday, while the Hong Kong Jockey Club cancelled its midweek horse racing.

Hong Kong’s stock exchange, which changed its rules this year to remain open during typhoons, said it was closely monitoring the situation.

Ragasa, named after the Filipino word for rapid motion, was expected to make landfall in Guangdong province within 24 hours.