Partygoers screamed, and those who didn't fall stood around the remaining edges of the floor and stared below in shock.
No individuals were trapped during the collapse and it's unclear if anyone suffered life-threatening injuries, police said. "Everyone was on the floor and people were screaming and there was wood sticking up from the floorboards".
Authorities are now investigating why the floor caved in.
Leroy Pearson said he went to try to help injured people and saw what he thought looked like broken ankles and legs.
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Police said a private party was being hosted by a group who leased the clubhouse.
As a crowded group of Clemson University students and local residents danced and jumped around at an apartment clubhouse, Jeremy Tester felt something odd beneath his feet.
The property management of the clubhouse told CNN it was built in 2004. I can tell you there was a floor collapse.
Clemson University President Jim Clements said on Twitter that he is monitoring the situation, and the school tweeted that student affairs representatives were sent to the hospitals where the injured were taken. There were injuries. They were not life-threatening.
According to police said a call was received about 12.
The clubhouse building where the collapse happened is a common area within the complex. From there, the homeowner's association will determine how to rebuild the clubhouse to make it safe for all residents.