Some 129 people are missing in Taiwan's eastern Hualien county after a barrier lake overflowed and sent a wall of water into a town, the Taiwan fire department said on Wednesday, with Ragasa's outer rim having drenched the island since Monday.
Many residents in the tourist town of Guangfu complained there was insufficient warning from Taiwan authorities, who are used to moving people out of potential danger zones swiftly on the island, which is frequently hit by typhoons.
As rain inundated Taiwan, Hong Kong grappled with huge waves that crashed over areas of the Asian financial hub's eastern and southern shoreline, breaking into white-water streams as they rushed along pavements and submerged some roads alongside residential properties.
At the Fullerton hotel on the island's south, videos on social media showed a torrent of seawater surging through its glass doors before flooding the floor area.
China's marine authority issued its highest "red" wave warning for the first time in 2025, forecasting storm surges of up to 2.8 metres in parts of Guangdong province, as Ragasa charges towards the densely populated Pearl River Delta.
Ragasa formed over the western Pacific last week.
Fuelled by warm seas and favourable atmospheric conditions, the tropical cyclone rapidly intensified to become a category five super typhoon on Monday with winds exceeding 260km/h.
It has since weakened to a category three typhoon, which is still capable of bringing down trees and power lines, shattering windows and damaging buildings.
"Authorities have taken lessons from Hato and Mangkhut, which both caused billions of dollars in damage in 2017 and 2018," said Chim Lee, a senior energy and climate change specialist at the Economist Intelligence Unit.
"The Pearl River Delta is one of the best-prepared regions for typhoons, so we're not expecting major disruptions. One change this year is that the Hong Kong stock market has stayed open during typhoons - a sign of how resilient the infrastructure has become."
After passing about 100km south of Hong Kong in the next few hours, Ragasa is expected to cross the south Chinese coast in the late afternoon.
Guangzhou, Shenzhen, Foshan and Dongguan, the largest cities in the storm's path, are home to about 50 million people.
The emergency management ministry dispatched tens of thousands of tents, folding beds, emergency lighting equipment and other rescue supplies to Guangdong on Tuesday, Chinese state media reported, while over 770,000 people have been evacuated.
China's marine authority warned of a high risk of flooding in Shenzhen, especially in low-lying areas, with a storm surge alert expected to remain in effect until Thursday.
A woman and her five-year-old son were swept into the ocean on Tuesday after watching the typhoon from the Hong Kong waterfront, according to the South China Morning Post, which said they were now in intensive care.
Hong Kong lowered its typhoon signal to 8 from 10 just after 1pm on Wednesday, keeping the city locked down.
The hospital authority said at least 50 people had been injured by the typhoon, while the government had opened 50 temporary shelters, within which 791 sought refuge.
In the gambling hub of Macau next to Hong Kong, casinos were forced to shutter their gambling areas.
Guests are not able to leave their property if they are staying there.
One user on China's Xiaohongshu app showed videos of doors being sealed at a casino resort for protection against gales and debris.
