David Jackson, and Eliza Collins

USA TODAY

Hillary Clinton, who unexpectedly left a 9/11 event in New York City because of the heat, was diagnosed with pneumonia two days ago, her campaign said Sunday.

"While at this morning's event, she became overheated and dehydrated," said a late afternoon Sunday statement from Dr. Lisa R. Bardack. "I have just examined her and she is now re-hydrated and recovering nicely."

Bardack said that Clinton "has been experiencing a cough related to allergies. 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."

During a 9/11 commemoration ceremony, the Democratic presidential nominee "felt overheated" and left for daughter Chelsea's apartment in New York City, said Clinton spokesman Nick Merrill.

A Twitter video posted under the account Zdenek Gazda showed a wobbly looking Clinton being helped into a van upon leaving the memorial service.

The Clinton campaign did not disclose the pneumonia diagnosis until after the Sunday incident.

New York temperatures on Sunday were in the low 80s, with humidity in the mid-40s.

The Democratic nominee left her daughter's home shortly after 11:45 a.m., waving at people gathered on the sidewalks.

Clinton also hugged and took a picture with a little girl who was allowed past the security line.

Video of Clinton leaving Chelsea's apartment:

Asked if she was feeling better, she said: "Yes ... thank you very much."

Clinton also told reporters: "I'm feeling great. It's a beautiful day in New York."

The incident came as the campaign of Republican nominee Donald Trump has made various claims about Clinton's health. In a column in USA TODAY, former New York major Rudy Giuliani said there are unanswered questions about Clinton's health, although he added that "I hope Secretary Clinton is perfectly healthy."

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