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A doctor who was aboard the California-bound JetBlue flight that was forced to make an emergency landing in South Dakota after two dozen people were hurt by turbulence said Friday it was so bad passengers were tossed around the cabin like rag dolls.

"People who didn't buckle their seat belts were flying up and hitting the ceiling," Alan Lee told NBC News.

Three flight attendants standing in the back were also knocked off their feet, he said.

"They are professionals and they are fine with turbulence," Lee said. "All three of them hit the ceiling with their heads. One of them went through the ceiling tile. That is what caused the injuries that forced the landing in South Dakota."

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Lee said when he went back to check on them "there was a lot of turbulence."

"Even as I walked back the plane was still shaking," he said. "There was a lot of debris around, a lot of bags everywhere, drink containers all over the back."

The twenty-four people injured — which included two crew members on Flight 429 — wound up being sent to the hospital for evaluations after the plane was diverted to Rapid City on Thursday evening, officials said.

All were treated for minor injuries and had been released by early Friday, Rapid City Regional Hospital told NBC News.

Lee, an orthopedic surgeon flying to Sacramento to start a new job on Monday, said he was working on his laptop when the plane began to shake.

"There was a lot of turbulence already," he said. "There there was a sharp drop. My laptop almost hit the ceiling."

Lee said passengers had been warned to return to their seats before the turbulence got really bad. "It was made very clear by the pilot and flight attendants that we should be seated and buckled in," he said.

"It got really rocky," passenger Victor Rosales told NBC News via Twitter message. "We felt like a giant hand hit the plane … I saw stuff fly everywhere."

Jet blue scary ride... pic.twitter.com/q9iFTgmKeJ — Rhonda Renee (@Bistrobaby) August 12, 2016

For the rest of the passengers, JetBlue dispatched a replacement plane so they could continue on to Sacramento.

Passenger Christopher De Vries was among those waiting early Friday for it with his daughters. He told NBC News he's glad he's been a "stickler" for reminding them to fasten their seat belts.

"They would have flown out of their seats had they not been strapped in," he said via Twitter message.