CHEONGJU, South Korea The bodies of six people trapped in a tunnel submerged by heavy rains in central South Korea were retrieved on Sunday, firefighting authorities said, taking the death toll from days of torrential rains that have pounded the country to 33.

Seo Jeong-il, head of the west Cheongju fire station, said some 15 vehicles, including a bus, are estimated to have been submerged in the flooded underpass in the city.

"We are focusing on the search operation as there's likely more people there," Seo told reporters. "We are doing our best to wrap it up today."

The death toll in the tunnel stands at seven, he said.

The Ministry of Interior and Safety said 10 people were missing as of 11 a.m. (0200 GMT) as heavy downpours caused landslides and floods across the country, with evacuations covering 7,866 people.

The ministry data does not include those in the flooded tunnel as it was not immediately clear how many people were trapped underwater.

Korea Railroad Corp has halted all slow trains and some bullet trains since Saturday due to safety concerns over landslides, track flooding and falling rocks.

President Yoon Suk Yeol, now on an overseas trip, ordered Prime Minister Han Duck-soo to mobilise all available resources to minimise the casualties, his office said, as more heavy rain was expected on the Korean peninsula on Sunday.

(Reporting by Do Gyun Kim, Daewoung Kim and Hongji Kim in Cheongju, Soo-hyang Choi in Seoul; Editing by Diane Craft and Michael Perry)