Police remove trees from a four-lane street during rush hour in front of Dongmyo subway station in Seoul on Thursday. (Jo Yong-Hak/Reuters)

Typhoon Kompasu struck South Korea early Thursday, killing three people while it knocked over streetlights and scaffolding in what was called the strongest tropical storm to hit the Seoul area in 15 years.

Powerful gusts knocked over power lines, cutting off power to tens of thousands of homes and forcing airports to cancel or delay dozens of international flights, the National Emergency Management Agency said.

Streets of Seoul, the capital, were littered with tree leaves and branches and toppled construction. Some parked cars were wrecked by scaffolding knocked over by the typhoon.

More than 60 international flights were delayed or cancelled, mostly to and from China, officials at Incheon and Gimpo airports said. Service on two Seoul subway lines and five railway routes was suspended ,the emergency management agency said.

An 80-year-old man died after being hit by a roof tile and a 37-year-old businessman was killed on his way to work by a falling tree branch, the agency said. A 75-year-old man was electrocuted while examining a transformer, and four people were injured by broken glass.

Elementary and middle schools Seoul were ordered to delay the start of the school day by two hours, while all public and private kindergartens were closed for the day, the Seoul Metropolitan Office of Education said.

The storm caused at least $8.3 million US in damage to a soccer stadium in Incheon, west of Seoul, stadium officials said.

Power was out at more than 60,000 homes along South Korea's west coast, officials said.

Kompasu, the Japanese word for "compass," landed on Ganghwa Island, about 70 kilometres west of Seoul, early Thursday morning, officials said.

Heavy rain hits North Korea

The typhoon also caused torrential rains and heavy gusts throughout North Korea, the country's state media reported Thursday. It didn't say whether the typhoon caused any casualties or damage.

Last month, floods swamped farmland, houses and public buildings in the North's northwestern city of Sinuiju and adjacent areas and displaced more than 23,000 people, according to figures by the International Federation of Red Cross and Red Crescent Societies.

Earlier this week, South Korea's Red Cross offered the North relief aid worth $8.3 million US.