Two people have died and more than 17 were injured, after an internal balcony collapsed at a nightclub in the South Korean city of Gwangju early on Saturday, the local fire service says.
Several athletes at the World Swimming Championships were slightly injured, Yonhap news agency reported.
They are from the US, New Zealand, the Netherlands, Italy and Brazil.
Two South Koreans were taken to hospital in a serious condition and later died, Yonhap reports.
The deceased were 38 and 27, and were not competitors at the championships.