South Korean officials evacuated thousands of coastal residents Thursday as a powerful tropical storm started to pummel the country’s southern regions.

The Korean Meteorological Administration said Khanun will make landfall soon and likely pound the country with intense rains and winds while slowly plowing through the Korean Peninsula for hours, with its eyes brushing the densely populated Seoul metropolitan area where half of South Korea’s 51 million people live.

The storm’s strength is expected to be diminished when it moves on to North Korea early Friday, but forecasters said the greater Seoul area would still feel its force until Friday afternoon.

More than 10,000 people, mostly in the country’s southern regions, were ordered to evacuate from their homes as of Thursday morning, the Ministry of the Interior and Safety said. Around 340 flights were grounded and nearly 400 motorways were shut down. Ferry services were halted while more than 60,000 fishing vessels evacuated to port. Authorities advised schools to take the day off or delay their opening hours, issuing warnings about flooding, landslides and huge waves triggered by what forecasters describe as typhoon-strength winds.