The Korea Meteorological Administration warned of “very heavy rain and very strong winds” as Typhoon Haishen, packing maximum winds of 78 miles per hour, made landfall in the southeastern port city of Ulsan.
Cars struggled to navigate flooded roads in Ulsan and other coastal cities.
Emergency workers scrambled to clean up toppled trees and damaged traffic signs, buildings, and other structures.
The Ministry of the Interior and Safety said a person in Busan was lightly injured after a car flipped in strong winds, but it did not immediately provide further reports of casualties.
At least 318 flights in and out of the southern island province of Jeju and across the mainland were cancelled, according to the Korea Airports Corporation.
Some bridges and railroad sections were shut down, thousands of fishing boats and other vessels were moved to safety, and more than 1,600 residents in the southern mainland regions were evacuated due to the possibility of landslides and other concerns.
Meanwhile traffic in southern Japan was still paralysed even after the typhoon passed.
Bullet trains were suspended and most domestic flights in and out of southwestern Japanese airports were cancelled on Monday.
The Japan Meteorological Agency warned strong winds and torrential rain would continue even after the typhoon moved north.
The storm slammed Okinawa and other islands over the weekend with heavy rain, rough waves and high tides.
The Fire and Disaster Management Agency said that at least 20 people were injured in several southern prefectures.
As of Monday morning, about half a million homes were still out of power.
Haishen is the second typhoon in less than two weeks to take a similar path through southern Japan and the Korean Peninsula.
Typhoon Maysak last week injured dozens of people and damaged homes and other buildings.
A livestock cargo ship capsized and sank off Japan’s coast during stormy weather as Maysak passed.
Two of its 43 crew members were rescued and one body was recovered before the search was halted because of Haishen.
The ship was transporting 5,800 cows from New Zealand to China.
