Two people died and seventeen were injured after a balcony gave way at the Coyote Ugly nightclub in South Korea.
A number of those injured were foreign athletes competing in the World Aquatics Championships.
The two people killed were South Korean while eight of the 10 injured were athletes.
For seven of them, only minor injuries were sustained but one had to stay in hospital for treatment of a leg laceration.
New Zealand men's water polo team captain Matt Small said he was on the second-floor deck when it collapsed in an interview with New Zealand's Radio Sport.
"We were just dancing and then the next minute we dropped," he said. "We fell on top of the heads of other people that were beneath us... Some of them were pretty dire cases."
Kim Young-don, chief of Gwangju Seobu Fire Station, said the floor collapsed from both the balcony and a staircase.
There were 370 people in the club at the time:
"We deem that the second level ... seems to have collapsed because there were too many people on it," he said. "The second level is a small space, it's not a space where a lot of people can be."
A Gwangju police officer told Reuters that two owners of the club, as well as two staff members, were being questioned over a possible illegal expansion and renovation at the nightclub and the legality of its licensing.
Public safety has been an important issue in South Korea after the 2014 sinking of the Sewol ferry which killed 304 people.
The administration of President Moon Jae-in has established a national system for accident prevention as well as making disaster management a priority. However, there have been several major incidents since he came to power.
In December of 2017, 29 people were killed and 40 injured in a fire at a fitness centre. A month after that, 45 people died and 147 were injured in a hospital fire.