Typhoon Hinnamnor, one of the most powerful to bear down on South Korea in decades, has hit the southern island of Jeju overnight before making landfall near the port city of Busan.
The typhoon killed one person and left nine missing on Tuesday, before heading back to sea, leaving thousands of people displaced and damaging properties.
The typhoon left the Korean peninsula at about 7:10am local time (22:10 GMT on Monday) through waters off the southeastern city of Ulsan after landing on the coastal city of Geoje, according to the Korea Meteorological Administration.
Early on Tuesday in the eastern port city of Pohang, a woman in her 70s was swept away in flooding and killed, the Central Disaster and Safety Countermeasures Headquarters said.
Death tolls could climb after the authorities identified at least nine people missing as of Tuesday afternoon, including seven people at a submerged underground parking lot in Pohang.
More than 60,000 households nationwide lost power because of the typhoon, which also forced hundreds of flight cancellations, suspension of business operations and school closures.