CLEMSON, S.C. — The floor of a clubhouse near Clemson University where a homecoming party was taking place collapsed early Sunday, hurtling dozens of people into the basement, authorities said.

About 30 people were taken to hospitals after the center part of the floor at the clubhouse in northwest South Carolina caved in during the annual homecoming weekend party sponsored by Kappa Alpha Psi fraternity.

It hadn't yet been determined how many of those injured at were Clemson students, the university said in a letter to students and faculty.

Video posted on social media showed a large part of a floor on the first level caving in as people were dancing, causing dozens to fall through to the floor below.

Larissa Stone, a sophomore at the university, told the Independent Mail of Anderson that the room was "packed" and that 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 on parts of the first floor that remained and gazed 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 that people were jumping and that then suddenly he heard "a boom."

"All you seen was falling, everybody's hands up in the air," Franzie Pendergrass told NBC affiliate WYFF of Greenville.

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 event was a private party by a group that had leased the clubhouse at The Woodlands Apartments, about three miles from Clemson.

According to police, a call was received about 12:30 a.m. Sunday about the collapse of the floor at The Woodlands clubhouse. Ambulances were quickly called to the scene.

Property manager Tal Slann told The Associated Press that the condominium complex was built in 2004-05. He said he couldn't 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.