Watch video of how Clinton Hillary collapsed while trying to enter her drive[video]

Hillary Clinton appeared to stagger and faint in footage showing her early exit from a 9/11 commemoration ceremony on Sunday, though Clinton's doctor said the episode was a result of heat and dehydration -- and revealed she had been diagnosed with pneumonia two days prior.

The Democratic presidential nominee fell on her way into her van and had to be helped by her security, according to witnesses and video of her leaving. She was “clearly having some type of medical episode," a law enforcement source told Fox News.


After more than an hour of radio silence, Clinton's campaign issued a statement saying the former Secretary of State "felt overheated," and later Sunday issued another release blaming the episode on pneumonia and dehydration.

"Secretary Clinton has been experiencing a cough related to allergies," Dr. Lisa R. Bardack said in the statement. "On Friday, during follow up evaluation of her prolonged cough, she was diagnosed with pneumonia. She was put on antibiotics, and advised to rest and modify her schedule. While at this morning's event, she became overheated and dehydrated. I have just examined her and she is now re-hydrated and recovering nicely."
But a witness told Fox News that Clinton stumbled off the curb, her "knees buckled" and she lost a shoe as she was helped into a van during her "unexpected early departure."

The New Jersey resident who took the video, Zdenek Gazda, told Foxnews.com he had been a fireman in the Czech Republic and came to the 9/11 ceremony to pay his respects.

"Everything was fine, everything was good before," said Gazda, who snapped several shots of Clinton before taking the video. "I take a lot of pictures of her. She looked very nice and everything, and I don’t know what happened to her."

After Clinton left the ceremony, the reporters following her on the campaign trail were prevented from leaving the media area for a period of time.