Video shows Hillary Clinton appearing to faint while getting in van

NEW YORK (WABC) -- Video taken at the scene of the 9/11 ceremony at ground zero and posted on social media shows Hillary Clinton appearing to faint before getting into her van.

The video, posted courtesy Zdenek Gazda Twitter, shows the Democratic nominee for president being held up by three people. She staggers and appears to trip on a curb as they help her into the vehicle.

Clinton abruptly left Sunday's 9/11 anniversary ceremony in New York after feeling "overheated," according to her campaign, and retreated to her daughter's nearby apartment. As she exited the apartment shortly before noon, Clinton said, "I'm feeling great."

Clinton's doctor says the Democratic presidential nominee was diagnosed on Friday with pneumonia, put on antibiotics and advised to rest and modify her campaign schedule.

A senior law enforcement official who was briefed on the matter said that after leaving the memorial plaza, Clinton was observed "fainting" in a departure area. That official spoke on condition of anonymity, because he wasn't authorized to disclose information publicly.

Clinton walked out of daughter Chelsea Clinton's apartment on her own and made only a brief comment to the reporters waiting outside, saying "It's a beautiful day in New York." She waved and posed for a photo with a young girl before getting into her motorcade.

(The Associated Press contributed to this report)