The incident occurred in the middle of the performance (about 1:45). Hyomin had just finished singing her part and was stepping to the side for Eunjung to step into the spotlight when she fell to the ground. Luckily she did not seem to be injured and stood back up to finish the performance.
Afterwards, Hyomin (@b29530) assured fans she was alright and tweeted, “Lots of things happened today. I accidentally fell down on stage. I should have been more careful because we will hold a concert the day after tomorrow. For the people who are worrying about me, I’m okay so don’t worry. I will be more careful.”
You can see the spill below: