At least seven people died in the South Korean capital of Seoul and metropolitan area overnight, authorities said on Tuesday, after torrential rain knocked out power and left roads and subways submerged.

The southern part of Seoul received more than 100mm (3.9 inches) of rain per hour on late Monday, with some part of the city having received 141.5mm of rain, the worst rainfall in 80 years, according to local media citing Korea Meteorological Administration (KMA).

The accumulated precipitation in Seoul stood at 420mm as of 5 a.m. Tuesday (2000 GMT Monday), with more rain forecast.

In the glitzy, highly concentrated Gangnam district, some buildings were without power and had been inundated, while cars, buses and subway stations were submerged, leaving people stranded. Some stores had also been under water.

At least five people died in Seoul and two others in the neighbouring Gyeonggi Province as of 6 a.m. Tuesday, the Central Disaster and Safety Countermeasures Headquarters said. Four died after being trapped in flooded buildings, one was electrocuted, one person was found under the wreckage of a bus stop, and another died in a landslide, it said.

At least nine people in the areas were injured, while six were missing.

The headquarters raised the crisis alert to the highest and requested public and private organisations to adjust their working hours.

The KMA issued heavy rain warnings across the capital and the metropolitan area as well parts of Gangwon and Chungcheong Province.

Such advisories are issued when precipitation is predicted to surpass 60mm in a span of three hours or 110mm in 12 hours.

The KMA expects heavy rainfall for the central part of the country to continue through at least Wednesday.