Hong Kong's weather observatory issued its highest storm warning alert - a signal T10 - and the normally bustling city was all but shut down as transport was suspended and torrential rain flooded roads and buildings.
Typhoon Mangkhut has claimed its first victims in China, with at left at least two dead in Guangdong province. It was the most powerful typhoon to hit Hong Kong since 1979, packing winds of 195 kilometers per hour (121 mph).
Tens of thousands of travelers had plans disrupted after Hong Kong's worldwide airport, a major regional hub, canceled most flights.
"The landslides happened as some residents returned to their homes after the typhoon", disaster response coordinator Francis Tolentino told DZMM Radio, adding that most of the 5.7 million people affected had made advance preparations.
The world's biggest storm this year felled trees and sent skyscrapers swaying in high-rise Hong Kong, injuring more than 200 people there before making landfall on the coast of Jiangmen city, in southern China's Guangdong province.
Hong Kong residents were being told to stay away from the coastline and be on alert for occasional gales.
Mangkhut struck the northern Philippines as a super typhoon, killing at last two people and causing flooding and landslides on the northern island of Luzon.
In Hong Kong, the storm injured 213 people and caused terror by shaking tall buildings, smashing windows and felling trees.
Philippine forecasters say Typhoon Mangkhut has slammed into the country's northeastern coast.
On Sunday, Mangkhut moved northwest to China, where it brought heavy rain and strong winds to several southern provinces.
Three people have already died as one of the strongest typhoons in the history of the Philippines makes landfall.
Boats were thrown onto the shore by powerful waves and the enormous rainfall has brought fears of landslides, although none have yet been reported in Hong Kong.
"Although Mangkhut has weakened slightly, its circulation is extensive and winds remain fierce", the HKO said. Its power is equivalent to maximum hurricane of the fifth category. Men used pikes and shovels to dig into the mud since the soaked ground was unstable and limited the use of heavy equipment on site.
A tropical cyclone packing winds of over 125 miles per hour (200kph), Mangkhut was at its most ferocious as it swept over the Philippines, before brushing past Hong Kong and slamming into China. At least seven bodies had been dug out Sunday before the work had ceased during the night.