South Korea’s Ministry of Internal Affairs and Security said three of the dead were trapped in a flooded semi-basement. Nine others were injured and at least seven people remain missing, the ministry said.
A total of 422 millimeters (16 inches) of rain fell in parts of Seoul as of midnight Monday local time, prompting authorities to raise the highest level 3 emergency alert. The city recorded 141.5 millimeters (5.57 inches) of rain per hour, the highest rate since authorities began keeping records.
Pictures from across the city showed heavy flooding, with people wading along roads up to their thighs in water.
Although the floodwaters had largely receded by Tuesday morning, cars and buses were scattered across roads and sidewalks, blocking morning traffic.
In some parts of Seoul, sewage backed up and water poured back onto streets and subway stations, according to the Seoul Metro. A number of metro stations were closed due to flooding, with lines temporarily suspended on Monday night. As of Tuesday morning, authorities were still working to reopen the stations.
Several regions south of the Han River were hardest hit, including the affluent modern district of Gangnam, where some buildings and shops were flooded and lost power.
About 800 residents were evacuated to schools and gymnasiums or voluntarily sought shelter in local community centers as floods affected more than 700 houses and shops, according to authorities.
He also pointed to the need to review the country’s disaster management system as extreme weather is expected to become more frequent due to the climate crisis.
Many countries in East Asia are now experiencing more intense daily rainfall, with summer monsoons expected to become stronger and more unpredictable as the Earth warms, according to the Intergovernmental Panel on Climate Change.
Heavy rain is expected to continue on Tuesday, with up to 100 millimeters (3.9 inches) of rain in some regions, according to the country’s Meteorological Administration.
Additional reporting by CNN’s Jake Kwon and Reuters.