The storm had raised Hong Kong's most severe Typhoon 10 warning, only the third time a storm of this power has pounded the financial hub in the past 20 years.
Eight people were killed in the gambling mecca of Macau, where local media showed cars underwater and people swimming along what are normally streets. The enclave's famed mega-casinos were running on backup generators.
One man died after being injured by a wall that blew down, another fell from a fourth floor terrace and another was a Chinese tourist hit by a truck, the Macau government said. Details on the two other victims there were not immediately available.
More than 120 were injured as the territory was lashed with hurricane winds and pounding rain, with police adding that one 83-year-old man earlier thought to be a victim had actually committed suicide during the typhoon.
In the southern Chinese province of Guangdong, at least four people died and 26,817 people evacuated to temporary shelters, the official Xinhua news agency said. Nearly two million households were briefly without power.
Source: LUSA / AAP
Authorities issued alerts over possible landslides and flooding as the typhoon continued on a path inland.
In Macau, people swam through muddy water on what are normally roads, as others were swept off their feet by winds, footage from Apple Daily showed.
The sprawling Venetian casino resort was on back-up power and without air conditioning or proper lighting, according to one source.
An employee of Sands, which owns the Venetian and the Parisian, said power had been out across the whole of Macau but was beginning to return.
"Because many guests come in the summer, a lot of them have been stuck in the major resorts and casinos," the employee said.
"All transportations -- air, ground, sea -- have halted, so customers who have checked out cannot leave yet."
Residents took to social media to complain about city-wide power and mobile phone network outages.
Brian Chan, 31, said authorities had failed to give enough notice of the impending storm and were not properly prepared, describing the territory as "totally lost" in the typhoon.
Water supply was also limited, authorities said, and 50 flights cancelled from its international airport.
By evening, parts of Macau were still without power.
"Some have no tap water supply. The city looks like after an attack," Harald Bruning, editor of the Macau Post Daily, told AFP, describing it as the worst typhoon he had experienced in 30 years.
Pedestrians pass by a fallen tree after the passage of Typhoon Hato in Macau, China, 23 August 2017 (AAP) Source: AAP
'Flying trees'
The typhoon passed as close as 60 kilometres (37 miles) from Hong Kong and made landfall at noon (0400 GMT) in the southern mainland Chinese city of Zhuhai.
The typhoon shut down the stock market in the territory of 7.3 million people, and forced the cancellation of hundreds of flights.
Hato sent metres-high waves crashing into Hong Kong's shorelines with flooding knee deep in some areas.
Swathes of marine rubbish washed up on beaches and in coastal residential areas, including white globs of palm oil which have been coming ashore since a massive spillage at sea earlier this month.
Gusts of up to 207 kilometres per hour brought flying debris, tearing down trees and scaffolding and smashing skyscraper windows.
Fallen trees cut off roads to parts of the territory.
More than 400 flights were cancelled, with Hong Kong flag carrier Cathay Pacific axing most of its departures until 5 pm (0900 GMT).
The airline said it had begun to reschedule the flights with some taking off Wednesday evening.
Hong Kong is regularly besieged by typhoons between July and October, but direct hits are rare.
The city saw its strongest storm in 1962 when the eye of typhoon Wanda passed over and gusts of 284 kilometres per hour were recorded.
It killed 130 people and left 72,000 people homeless.
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