Hong Kong was flooded by the heaviest rainfall in nearly 140 years on Friday, leaving 83 people hurt and the city’s streets under water.
Just across the border, authorities in China’s city of Shenzhen also recorded the heaviest rains since records began in 1952.
Authorities issued flash flood warnings, with emergency services conducting rescue operations in parts of Hong Kong.
It also warned of potential landslides, telling motorists to “keep away from steep slopes or retaining walls”.
The torrential rain was brought by Haikui, a typhoon that made landfall in the Chinese province of Fujian on Tuesday.
Although it weakened to a tropical depression, its slow-moving clouds have dumped huge volumes of precipitation on areas still soaked by rain from a super typhoon a week earlier.
The heavy rainfall in Hong Kong started on Thursday and in the hour leading up to midnight, the city’s weather observatory recorded hourly rainfall of 158.1 millimetres, the highest since records began in 1884.
“It’s absolutely shocking,” said Jacky, 52, who lives in the Wong Tai Sin district with his elderly parents. “I don’t remember floods ever being this bad in our district.
“The bottom floor of the mall is completely flooded, the water level is higher than the storefronts... it’s turned our day into chaos.”
Olivia Lam, who lives on the eastern side of Hong Kong, added: “It felt like the whole neighbourhood was isolated by the floodwater. One of the underground car parks is totally underwater.
“The water was almost waist-deep outside my building, and that’s not the worst (case) in the neighbourhood.”
Hong Kong authorities shut schools on Friday and told workers to stay at home. The city’s stock exchange was also closed.
Eric Chan, secretary for administration, said the city’s transport network was “severely disrupted” and an “extreme conditions situation” would be extended to midnight on Friday.
MTR Corp, which operates the city’s rail network, said at least one line was shut while others were operating with delays. One video clip showed metro workers wading waist-deep in a station.
Some roads were partly washed away, including a main route to the city’s southern beaches. A car was swallowed up by a metres wide pothole when one section of road collapsed.
Government officials said “extreme conditions” will last until at least 6pm, while the hospital authority said more than 80 people had sought help at emergency rooms.
On Friday morning, taxis struggled through flooded roads as commuters attempted to make their way to work. Some cars were left stranded in the deluge.
In the Shau Kei Wan district, a landslide blocked a two-lane road.
“It’s a bit of a painful experience,” said Eli, a stranded commuter, adding that he had “no chance” of making it to his destination on the south side of Hong Kong.
Roads were also flooded on the island of Lantau, where rivers swelled over their banks.
Southern China was hit the previous weekend by two typhoons in quick succession - Saola and Haikui - although Hong Kong avoided a direct hit.
Tens of millions of people in the densely populated coastal areas of southern China had sheltered indoors ahead of those storms.
Hong Kong’s weather observatory said the latest torrential rain was brought by the “trough of low pressure associated with (the) remnant of Haikui”.