Typhoon Hato, a maximum category 10 storm, has slammed into Hong Kong and Macau with destructive winds and waves which uprooted trees, flooded streets and forced most businesses to close.
Three people have died and two gone missing in Macau, according to a Civil Defence Centre announcement reported by the South China Morning Post.
One of those killed was a 30-year-old man who was hit by a falling wall, the report said.
In Hong Kong more than 400 flights were cancelled, financial markets suspended and all schools were closed as Hato bore down on the city, the first category 10 storm to hit Hong Kong since typhoon Vicente in 2012.
It was later downgraded to a category 8 storm as it moved towards Guangdong province in China.
Many skyscrapers in the heart of Hong Kong were empty and in darkness as the city's workers stayed at home and hunkered through the storm.
Hato churned up Hong Kong's iconic Victoria Harbour and triggered large swells and massive waves on some of the city's most popular beaches, with serious flooding in low-lying areas.
In residential districts like Heng Fa Chuen on densely populated Hong Kong island, massive waves smashed against the sides of oceanfront buildings and surged over a promenade, swamping vehicles parked nearby.
Construction cranes swayed precipitously from the tops of skyscrapers, trees toppled and residents deployed canoes to get around on some streets.
"I've never seen one like this," said Garrett Quigley, a longtime resident of Lantau island to the west of the city.
"Cars are half submerged and roads are impassable with flooding and huge trees down. It's crazy."
Maximum winds near Hato's centre were recorded at a destructive 155km/h.
A senior scientific officer for the Hong Kong observatory said sea levels could rise up to 5m in some places, with the government issuing flood alerts and opening 27 temporary shelters across the city.
Winds intensified today, with the maximum sustained winds recorded at Tate's Cairn and Waglan Island at 77km/h and 72km/h, with maximum gusts of 103km/h and 86km/h respectively.
Trading in Hong Kong's financial markets was halted for the day, the stock exchange said.
A total of 420 airline flights to and from Hong Kong had been cancelled, said the Government.
The city's flagship carrier, Cathay Pacific, said the storm would "severely" impact flight operations. Hong Kong Airlines also suspended most of its flights.
- Reuters, AAP