About 30 people were taken to local hospitals after the center of the floor caved in at the clubhouse near the South Carolina university. Clemson City Police said nobody was trapped and none of the injuries appeared to be life-threatening.
Video posted on social media shows a large part of the first floor falling as people danced, causing many of them to tumble to the floor below.
Clemson sophomore Larissa Stone told the Independent Mail of Anderson that the room was "packed" and a popular song was playing when the floor collapsed.
"So everyone was jumping. The beat was about to drop and literally the whole floor collapsed," she said. "It happened so quickly. I stood up, and everyone was trying to climb out. People are under other people. People are hurt. People are bleeding. I had blood on my sneakers. It was really bad."
Partygoers screamed, and those who didn't fall stood around the remaining edges of the floor and stared below in shock. Some people standing on the sidelines pulled out their cellphones to record the floor collapse.
A witness who attended the party said people were jumping and he heard a sudden "boom."
"All you seen was falling, everybody's hands up in the air," Franzie Pendergrass told WYFF News 4.
Leroy Pearson said he went to try to help injured people and saw what he thought looked like broken ankles and legs.
"It was crazy," Pearson said.
Police said the clubhouse at The Woodlands, about three miles from Clemson, had been leased for a private party.
Property manager Tal Slann told The Associated Press that the condominium complex was built in 2004-2005. He said he could not comment on whether there was a limit on the number of people who were supposed to use the clubhouse at one time.
"I can tell you there was a party. I can tell you there was a floor collapse. There were injuries. They were not life-threatening. Nobody was trapped," he said.
Police said they were called about 12:30 a.m. Sunday. Ambulances rushed to the scene.
Slann sent residents of The Woodlands an email saying the floor in front of the clubhouse fireplace had collapsed during a party.
"The Clubhouse and pool area is OFF LIMITS to all," said a copy of the email texted to the AP. "The clubhouse will be inspected by structural engineers as soon as possible. From there, the homeowner's association will determine how to rebuild the clubhouse to make it safe for all residents. Our thoughts and prayers are with all those who were injured and we apologize for any inconvenience."
Associated Press writer Janet McConnaughey contributed to this report from New Orleans.
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