About 250 to 300 millimeters (7.8 to 11.8 inches) of rain fell in parts of Seoul and nearby cities Paju, Incheon, and Gimpo through Thursday morning, leaving vehicles stranded on roads that became chocolate-colored rivers and residents salvaging belongings from properties damaged by flash floods.
Authorities issued flood and landslide warnings for areas near rivers, streams, and hills, while emergency workers rescued at least 145 people and responded to hundreds of reports of road disruptions.
As of Thursday morning, power was restored to some 4,000 households that had been knocked out of electricity overnight, the Ministry of the Interior and Safety said.
South Korea's weather agency said the greater Seoul area will continue to be affected by downpours through Thursday morning. Authorities shut down dozens of riverside parks and more than 100 hiking trails while issuing text messages warning people to beware of floods, landslides and damaged structures. No immediate flights were interrupted by the rain.