At least nine people were killed and 14 others injured when a sudden large waved crashed over a breakwater and swept them into the Yellow Sea off the west coast of South Korea, the coast guard said.
The wave — believed to have been as high as 16 feet — slammed over the breakwater near a beach southwest of Seoul where dozens of people had been fishing and sightseeing Sunday, said Lee Won-il, a Korea Coast Guard officer.
The dead included two children aged 9 and 5, and two of the injured — including another 9-year-old — were in critical condition, Lee said.
Witnesses described scenes of grief and panic after the wave washed over the breakwater at Daecheon Beach in the city of Boryeong some 120 miles southwest of Seoul.
"All of a sudden, there was a sound of thunder and lightning and then people screaming," Ko Myung-rae, the owner of a restaurant in the area, was quoted as saying by Yonhap news agency.
"Children were crying, saying 'Our mother died,'" he said. "As I looked at the sea, I saw people floating there."
Officials planned to search the area through the night as a precaution, Lee said, although apparently people who had initially been reported missing had been accounted for.
Thirty-six coast guard, navy and private fishing boats and 25 scuba divers participated in the search, while about 200 coast guard and fire department personnel and government officials were helping on shore, Lee said.
South Korea's weather agency had forecast strong winds and high waves in the area but did not issue an advisory, Lee said.
The wave was believed to have been caused by regular tidal movements in the Yellow Sea, he said, adding that it had been cloudy and drizzly when the incident happened.