Eight people died in the South Korean capital Seoul and the surrounding area on Tuesday night during the heaviest rainfall in decades.
Seven others were still missing as of Tuesday night.
The torrential rains flooded basements and cars, streets and subways.
In a Seoul borough, two sisters and one of their daughters died in a basement apartment from which they could not be rescued in time.
Several subway lines and city highways were temporarily closed on Tuesday morning.
According to the Yonhap news agency, a weather station in the Dongjak district of Seoul measured 381.5 millimeters of precipitation on Monday, more than at any time since modern weather records began in 1907. Heavy rainfall has also been announced for South Korea in the coming days.