Updated

Strong winds and hard rain pounded southern South Korea on Thursday, as the second typhoon this week barreled down on the Korean Peninsula only days after 20 people died or went missing in the South in the first storm.

North Korea was also in Typhoon Tembin's path, raising new worries about a country that is still rebuilding from devastating floods in late June. Casualties in the North from this week's first typhoon have yet to be reported, but that storm knocked out power, submerged roads and houses and ruined farmland, state media said.

The new storm was also hampering the search for seven missing fishermen who were on two Chinese ships that hit rocks off a southern South Korean island during the first typhoon, which was called Bolaven. Eight fishermen on those ships were among the 13 people killed in South Korea. The coast guard rescued 12 fishermen from the ships on Tuesday, and six others swam or were washed ashore.

On Thursday, the coast guard said it couldn't send ships to search for the missing fishermen because of high waves from Typhoon Tembin, though officers searched the shorelines.

Tembin was expected to weaken as it reaches North Korea. Heavy rain, however, can be catastrophic in the North because of poor drainage, deforestation and decrepit infrastructure. The North's official Korean Central News Agency said some areas of Hwanghae and Kangwon provinces could receive up to 70 millimeters (2.8 inches) of rain on Thursday and Friday.

South Korea issued a typhoon warning in many southern areas because of Tembin's strong winds and heavy rain, according to the National Emergency Management Agency. Tembin is weaker than the first typhoon, but more than 170 flights were canceled Thursday, the agency said.

In North Korea, Bolaven shattered rooftops and pulled trees up by the roots, breaking branches and trunks alike. High waves pounded boats floating near a seawall.

The storm also ripped off a power station's roof, submerged or destroyed houses, triggered landslides that buried railroads, cut power lines and damaged more than 8,500 hectares (21,000 acres) of maize fields, hurting the chances of a successful harvest, according to KCNA.

In South Korea, Bolaven temporarily left hundreds of thousands without power, canceled flights and damaged farmland. Nearly 100 families were left homeless.

More than 170 people died in North Korea in the floods in late June, and tens of thousands of homes were destroyed, according to official North Korean accounts.

Many flood victims still live in tents with limited access to water and other basic facilities, the U.N. report said, and there is worry about increased malnutrition in coming weeks.

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Associated Press writers Foster Klug and Sam Kim contributed to this report.