The Gwangju Fire and Safety Headquarters said the loft inside the nightclub collapsed around 2:30 a.m. and claimed the lives of two South Koreans. Authorities suspect the loft collapsed due to too much weight. Witnesses said there were about 100 people on the loft area, which was 2.5 meters above the lower floor.

Firefighters said 17 people were injured, including foreign athletes who came to Gwangju, some 330 kilometers south of Seoul, for the July 12-28 FINA World Championships. 

So far, authorities confirmed that nine foreign athletes were injured -- four Americans, two New Zealanders, one Dutch, one Italian and one Brazilian. They are all water polo players except the Brazilian, authorities said, with six of them women. 

Firefighters said their injuries are not severe, although some of them have underwent minor surgery after suffering lacerations. Among the foreigners on the injured list also include two Uzbek men who were not athletes. 

Local authorities believe dozens were injured from the collapse if those who suffered light bruises and scratches are included.

There were about 370 people inside the nightclub when the collapse occurred, they said.

The authorities said some of the loft space inside the nightclub was illegally expanded without the city's authorization.

Gwangju police said it will form a task force team to investigate the matter. 

The municipal government of Gwangju and local organizing committee of the FINA Championships said they will give their utmost support to help athletes who sustained injuries from the incident. (Yonhap)