Ragasa edged away from densely-populated Hong Kong and made landfall in Guangdong, after Hong Kong's weather service ranked the storm the strongest yet in the northwestern Pacific this year.

The typhoon's passage in Taiwan killed at least 15 and injured 18 when a decades-old lake barrier burst in eastern Hualien county under the storm's heavy rains, according to regional officials.

Authorities earlier said 152 people were unaccounted for, but later revised that figure down to 17, saying that they have made contact with more than 100 of those previously deemed missing.

More than 7,600 people were evacuated due to Ragasa and footage released by the fire agency showed flooded streets, half-submerged cars and uprooted trees.

The typhoon trampled parts of the northern Philippines earlier this week and killed at least eight people, including seven fishermen.

Scientists warn that storms are becoming more powerful as the world warms due to the effects of human-driven climate change.

Authorities across mainland China ordered businesses and schools to shut down in at least 10 cities across the nation's south, affecting tens of millions of people.

The storm made landfall along the coast of Hailing Island, near Yangjiang City around 5 pm (0900 GMT), Chinese meteorologists said.

Streets were mostly empty as winds intensified on Wednesday afternoon in Yangjiang, which lies west of Hong Kong.

An AFP journalist saw flying debris carried by strong wind that ripped advertisements off of buildings, as well as broken fences and fallen branches on the ground.

The Yangjiang train station -- normally bustling with activity, locals said -- stood empty, with rail travel suspended Wednesday across the province of Guangdong.

The casino hub of Macau -- which also saw widespread flooding -- has suspended power supply to some low-lying areas, according to utility company CEM.

- Hong Kong battered -

Hong Kong authorities said 82 people have been treated for injuries sustained during the typhoon period at public hospitals as of Wednesday noon.

More than 860 people sought refuge at the 50 temporary shelters across the city.

The Chinese finance hub recorded hundreds of fallen trees and flooding in multiple neighbourhoods. Many of the city's tall buildings swayed and rattled in the harsh winds.

At the Fullerton Ocean Park Hotel, next to a theme park, a man was seen losing his balance after storm surge shattered the glass front doors and swept into its lobby, according to a video circulated online and verified by AFP.

A hotel spokesperson said there were no injuries.

Floodwaters rushed into the seaside Heng Fa Chuen residential estate and covered its interior courtyards, another video clip showed.

"It's like the end of the world... I never expected to see it as bad as this," said IT manager Paul Yendle near a heavily damaged restaurant in the Tseung Kwan O area, another area near the harbour.

An off-duty firefighter surnamed Tse told AFP he was "a bit worried" about the safety of nearby bamboo scaffoldings as he walked home after an 11-hour shift of "non-stop" work.

Rail operator MTR said it will take time for workers to check and repair outdoor sections of train tracks.

The Airport Authority said "only a limited number of cargo flights" were scheduled for Wednesday, with its website listing hundreds of cancelled passenger flights.

A five-year-old boy and his mother fell into the sea on Tuesday afternoon while they were watching the waves in the Chai Wan district, according to police.

Both were rushed to hospital and the mother remained in critical condition on Wednesday morning.