Most of Hong Kong and southern China ground to a near standstill on Friday, with flights cancelled and schools closed as powerful Super Typhoon Saola closed in.

Many workers stayed at home, and trading on Hong Kong’s stock market was suspended, while authorities in mainland China halted all trains entering or leaving Guangdong province.

The Hong Kong Observatory issued a number 10 hurricane signal, the highest warning under the city’s weather system and the first of that strength since Super Typhoon Mangkhut in 2018.

More than 400 flights were cancelled or delayed in the key centre for regional business and travel, while nearly 4,000 trains will be out of service until Sunday.

Saola, with maximum sustained winds of 121mph, poses “a high threat” to the territory, said the Hong Kong Observatory, which warned of serious flooding in coastal areas and said the maximum water level might be similar to when Mangkhut felled trees and tore scaffolding off buildings in the city.

In recent months, China has experienced some of its heaviest rain and deadliest flooding in years in various regions, with scores killed, including in outlying mountainous areas near the capital, Beijing.

Weather authorities in the gambling hub of Macao also warned of flooding, forecasting that water levels might reach five feet in low-lying areas on Saturday morning.

China’s National Meteorological Administration said Saola could make landfall in coastal areas from Taishan city in Guangdong province to Shenzhen early on Saturday, or just skim across those regions.

It warned Saola could be “the strongest typhoon to make landfall in the Pearl River Delta since 1949” in a post on Weibo.

According to the state-run Global Times, more than 100,000 people have been evacuated in eastern China’s Fujian province.

Cathay Pacific announced the cancellation of all flights to and from Hong Kong from 6am on Friday to 2am on Saturday. A budget airline, HK Express, said it decided to cancel 70 flights scheduled for Friday and Saturday into and out of Hong Kong.

Meanwhile, China’s Ministry of Transport has dispatched 16 rescue-and-salvage ships and nine rescue helicopters to regions expected to be affected by the storm, according to state news agency Xinhua.

Saola veered just south of Taiwan on Wednesday before changing course to mainland China. The storm’s outer bands brought torrential rain to the southern cities of Taiwan.

It moved through the northern Philippines as well and led to the displacement of thousands of people. However, there have been no reports of direct casualties at this point.

Associated Press and Reuters contributed to this report