South Korean emergency workers have pulled at least six bodies from a flooded tunnel in the central city of Cheongju, officials said Sunday.

Authorities said at least 15 vehicles, including a bus, had been trapped in the flooded underpass.

Seo Jeong-il, head of the west Cheongju fire station, said workers are continuing to search the tunnel.

“We are focusing on the search operation as there’s likely more people there,” Seo said.

Heavy rains in recent days have forced thousands of South Koreans to evacuate their homes and have left thousands more households without electricity.

The heavy downpours have triggered landslides and flash floods.

South Korean President Yoon Suk Yeol, who is in Europe, has called for the government to mobilize all available resources to deal with the disaster.