Torrential rain continued to pound Hong Kong Friday — causing schools, offices and even the stock exchange — to close after a night of flash flooding that turned streets into raging rivers that looked better suited to white-water rafting than city living.

Parts of southern China also experienced drenching rains, including the tech metropolis of Shenzhen, where schools and businesses were also closed on Friday.

As the rains continued to fall, the Hong Kong city government announced at midday Friday that the “black alert” extreme weather warning would remain in effect until at least 6 p.m.

Earlier, it said schools would be closed all day, and only essential employees should report to work. The Hong Kong Stock Exchange canceled trading, including the after-hours session, for the entire day.

Hong Kong Chief Executive John Lee said he had ordered all city government departments to respond to the extreme weather with “all-out efforts.”

The city on Thursday night experienced its most intense hour rainfall since records began 140 years ago. Hong Kong weather authorities issued a black warning, an alert that more than 70 millimeters (2.75 inches) of rain was expected to fall in an hour, at 11:05 p.m. Thursday.

More than double that amount came down — the Hong Kong Observatory said that 158.1 mm (6.22 inches) of rain fell at its headquarters between 11 p.m. and midnight, according to the South China Morning Post.

In other parts of Hong Kong — Kowloon, the northeastern New Territories and Hong Kong Island — more than 200 mm (7.87 inches) of rainfall was recorded between 6 p.m. and midnight, the paper reported.

Photos and video shared on social media showed flooded streets, inundated subway stations and swamped city buses.

Water poured into the Cross-Harbor Tunnel, which connects Hong Kong Island with Kowloon, clogging up one of the city’s essential arteries. Rubble and water rushed down the side of Mount Parker near Chai Wan, where roads and parking garages sat under standing water.

More than 20 buses remained stranded across the city on Friday morning, according to the South China Morning Post, and the city’s three main bus carriers suspended service until further notice. The metro was largely operational.

In southern China, schools were closed Friday in Shenzhen, Zhuhai and parts of Guangzhou and Foshan.

Authorities in Shenzhen warned people Friday morning not to enter the central Longgang district, according to local media. People and businesses on ground floors of buildings in the district were urged to evacuate.

Social media posts showed that flooding overnight in Longgang had left dozens of vehicles swamped at major intersections.

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The region has been battered by two typhoons in two weeks, with Saola and Haikui wreaking havoc across Taiwan and southern China, although Hong Kong was not the direct path of either.

Vic Chiang and Theodora Yu contributed to this report.

By mrtrv