HONG KONG (AP) — Most of Hong Kong and parts of southern China ground to a near standstill Friday with classes and flights canceled as Super Typhoon Saola edged closer.

The typhoon could make a landfall in southern China and many workers stayed at home. Students in various cities had the start of their school year postponed to next week. Hong Kong’s stock market trading was suspended and more than 400 flights were canceled or delayed in the key center for regional business and travel.

China Railway Guangzhou Group said nearly 4,000 trains were suspended between Thursday and Sunday, state media CCTV earlier reported.

The Hong Kong Observatory raised a No. 8 typhoon signal, the third-highest warning under the city’s weather system, early Friday. Its forecast said Saola — with maximum sustained winds of 210 kilometers (130 miles) per hour — would be “rather close” to the financial hub on Friday and Saturday morning, skirting within 100 kilometers (62 miles) south of the city.

The observatory’s director Chan Pak-wai said on Thursday the alert might be upgraded to a No. 10 signal if the strength of the winds reached hurricane levels. The No. 10 hurricane signal is the highest warning under its system and was last hoisted when Super Typhoon Mangkhut hit Hong Kong in 2018.

Chan expected the winds would gradually weaken as the typhoon moves away from Hong Kong on Saturday.

The observatory warned serious flooding might occur in low-lying coastal areas and that the maximum water level might be similar to that when Mangkhut felled trees and tore scaffolding off buildings under construction in the city.

As the city braced for heavy rains and strong winds Friday morning, about 170 people sought refuge at temporary shelters, with some ferry and bus services halted. Residents living in low-lying areas had placed sand bags at their doors to prevent their homes being flooded.

Weather authorities in the nearby casino hub of Macao also warned against flooding, forecasting that the water level might reach up to 1.5 meters (5 feet) high in low-lying areas on Saturday morning.

In the technology and finance hub Shenzhen, its emergency management bureau ordered to suspend work and businesses starting from late afternoon as the typhoon was expected to make landfall in the city or its nearby areas on Friday night.

China’s National Meteorological Center said Saola could make landfall from Huidong County to Taishan city in Guangdong province, neighboring Hong Kong, between Friday night and Saturday morning. But it also did not rule out it would move west near the shore of central Guangdong.

As another storm Haikui was gradually moving toward the coastal areas of eastern China, coupled with the influence of Saola, parts of Guangdong, Fujian and Zhejiang provinces would see strong winds and heavy rains, according to a website run by China Meteorological Administration. By Thursday night, some 100,000 people living in dangerous areas in Fujian were relocated to other safer places.

Saola passed just south of Taiwan on Wednesday before turning to mainland China, with the storm’s outer bands hitting the island’s southern cities with torrential rain. The typhoon also lashed the Philippines earlier this week, displacing tens of thousands of people in the northern part of the islands because of flooding.

In recent months, China had some of the heaviest rains and deadliest flooding in years across various regions, with scores killed, including in outlying mountainous parts of the capital Beijing.