A Shaky Hillary Clinton Left 9/11 Memorial After Feeling 'Overheated'; Campaign Says She Has Pneumonia

The Democratic presidential nominee went to daughter Chelsea Clinton's apartment, saying she didn't feel well.

Democratic presidential nominee Hillary Clinton abruptly left Sunday’s 9/11 memorial service in New York City after feeling “overheated,” her campaign said.

Later in the day, it was revealed Clinton had been diagnosed with pnuemonia on Friday, after she sought medical treatment for a persistent cough.

Video posted to Twitter showed an apparently unsteady Clinton stumbling before being helped inside a large van by staff and Secret Service agents. In the video, Clinton seems to nearly collapse.

Hillary Clinton 9/11 NYC pic.twitter.com/q9YnsjTxss

September 11, 2016

She was taken to her daughter’s Manhattan apartment to recuperate, her staff said.

Dr. Lisa Bardack, Clinton's personal doctor, said in a statement that the candidate "has been experiencing a cough related to allergies," and she had been diagnosed with pneumonia on Friday "during follow-up evaluation of her prolonged cough."

Clinton was being treated with antibiotics and had been "advised to rest and modify her schedule," the doctor said.

Read: Where In The World Is Hillary Clinton? Candidate Hasn't Had a Press Conference in 272 Days

After she was escorted from the memorial service, her campaign issued a statment saying, “Secretary Clinton attended the September 11th Commemoration Ceremony for just an hour and thirty minutes this morning to pay her respects and greet some of the families of the fallen,” according to Clinton spokesperson Nick Merrill.

“During the ceremony, she felt overheated so (she) departed to go to her daughter’s apartment, and is feeling much better.”  Temperatures were in the 80s with high humidity Sunday.

The candidate stepped out of Chelsea Clinton’s apartment building around noon, and smiled and waved to reporters and supporters gathered outside.

She did not speak to journalists. In response to a shouted question asking if she felt better, Clinton said, “Yes, thank you very much.”

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She headed to her New York home in Chappaqua.

The incident quickly fueled online and television chatter about the candidate’s health, which Republican opponent Donald Trump has been lambasting as unstable while demanding she release her medical records.

Asked about Sunday's incident at the 15th anniversary service at the World Trade Center, Trump replied, "I don't know anything about it."

Former CIA deputy director Michael Morell, speaking to CNN's Jake Tapper Sunday, said he attended a national security meeting Friday with Clinton and "she looked fantastic. She had high energy.

"There are times in all of our lives when we don't feel well. I missed some of the briefings immediately after 9/11 because I wasn't feeling well," he said. "So let's not make more of this than there is."

During an August appearance on the Jimmy Kimmel program, Clinton called GOP claims about her health a "wacky strategy," and opened a jar to comically prove her strength.

Bardack has previously said Clinton suffers from seasonal allergies and that a blood clot and fainting spell she experienced in 2012 , which resulted in a concussion, left no lasting problems.

"She had follow-up testing in 2013, which revealed complete resolution of the effects of the concussion as well as total dissolution of the thrombosis (clot). Mrs. Clinton also tested negative for all clotting disorders," the doctor said in a statement recently released by Clinton's campaign.

Watch: Hillary Clinton Proves She's Healthy Enough To Be President