Taiwan evacuated thousands of people, closed down schools and halted rail services on Monday as Typhoon Nanmadol swept across some of the island's most densely populated areas.
The typhoon, which left at least 13 dead in the Philippines at the weekend, made landfall near the city of Taitung on the east coast of Taiwan in the early hours of Monday, according to the Central Weather Bureau.
"This is the worst typhoon to hit Taiwan since Morakot," which left more than 700 people dead or missing in 2009, a bureau official said.
The typhoon was slowly moving northwest, packing winds of up to 137 kilometres per hour (80 miles an hour), the bureau said, and was 30 kilometres northeast of the island's second-largest city Kaohsiung as of 0100 GMT.
Islandwide, authorities moved more than 8,000 people to safer places, according to the Central Emergency Operation Centre, as the first typhoon to hit Taiwan this year bore down.
The ministry of defence deployed thousands of troops to assist in evacuations, some navigating flooded areas in armoured personnel carriers.
TV footage showed soldiers walking through village streets in Pingtung county in southern Taiwan, helping people from homes threatened by flooding and putting them on military trucks.
The defence ministry also sent two C-130 transport planes to rescue 140 tourists marooned on the offshore island of Matsu, according to the Taipei Times newspaper.
The Taiwan Railway Administration suspended services on two rail lines from Taitung, the city where the typhoon had made landfall.
The typhoon brought torrential rain and some parts of Taiwan had received more than 500 millimetres of rain since early Sunday.
The Central Weather Bureau urged the public to stay away from mountainous and low-lying areas due to the threat of flash floods and landslides.
As of Monday morning, the Soil and Water Conservation Bureau had issued landslide warnings for more than 300 areas.
Businesses were closed in seven cities and counties in the south of Taiwan, and in all but two of the island's counties, classes were also cancelled at all schools.
Attention was also turned towards China, with the typhoon expected to gradually grind its way towards the Taiwan Straits during the course of Monday.
Southeast China's Fujian province called more than 25,000 fishing boats to port Sunday, amid warnings that moderate to heavy downpours would hit coastal areas from Monday morning, the official Xinhua news agency reported.