Dr. Dean Silas said some people died immediately after the stage fell.
"I helped where I could. For some people, it took the form of reassuring them; took the form of stabilizing their neck so then we could move them comfortably; and also carrying some of the folks out of the infield area to the grandstand area," Silas told ABC7 in a phone interview.
A gastroenterologist at Lutheran General Hospital, Silas pointed out that as many as 100 people were trying to help as soon as the accident happened.
Silas's daughter Jessica captured video of the stage collapsing. Shortly after the collapse, she and her mother ran for cover while her father helped the injured. She says she was with her visiting parents to see the concert.
"Watching the video itself, it's like something surreal. But you put the sound on it and you hear the people screaming. I don't like seeing it actually. It was bad," said Jessica Silas. "It's pretty much a freak event. You never think the stage would fall. Even if it did get windy it shouldn't happen, and the wind gust was before the storm even hit."