An accident during all-girl K-Pop group, 4Minute, performanced killed 16 people and 11 injured.

During a K-Pop music festival in Seoul, South Korea, a ventilation grate collapsed killing 16 people and injuring 11 others.

About 700 people attended the concert and many people were standing on a ventilation grate that eventually gave out, falling for about 20 meters, as reported on Pitchfork. During the accident, 4Minute had been performing on an outdoor stage.

The cause of the accident is not yet known.