US Democratic presidential candidate Hillary Clinton had to seek rest at her daughter’s apartment after feeling “overheated” at a 9/11 commemoration event, according to a statement from her campaign spokesperson.

According to the release, Clinton had been at the event for just over an hour when she began to feel ill.

“During the ceremony, she felt overheated so departed to go to her daughter’s apartment, and is feeling much better,” the statement from Nick Merrill reads.

Statement from Clinton camp says Clinton "overheated" at 9/11 ceremony: pic.twitter.com/TwJSjExKro — Kyle Griffin (@kylegriffin1) September 11, 2016

A video has appeared online purportedly showing Hillary Clinton getting into her car, evidently feeling unwell.

Hillary Clinton 9/11 NYC pic.twitter.com/q9YnsjTxss — Zdenek Gazda (@zgazda66) September 11, 2016

Fox News reported earlier, citing a law enforcement source, that Hillary Clinton had had a “medical episode.”

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.”

According to Fox News, reporters accompanying Clinton were “prevented from leaving the media area for a period of time” after the incident.

Two senior law enforcement sources told NBC that Clinton had to wrap up her visit to the 9/11 memorial after feeling “ill.”

BREAKING: law enf source: Hillary Clinton just left 9/11 ceremony w/medical episode, appeared to faint on way into van, helped by security — RickLeventhalFoxNews (@RickLeventhal) September 11, 2016

MORE ON #HILLARY per witness: "unexpected early departure"; she stumbled off curb, "knees buckled", lost a shoe as she was helped into van — RickLeventhalFoxNews (@RickLeventhal) September 11, 2016

Shortly afterwards, Clinton left her daughter’s house, saying she “was feeeling great,” the Associated Press reported.

The temperatures in New York reached over 84 degrees Fahrenheit (29°C) during Sunday’s event.

MOMENTS AGO: @HillaryClinton leaves daughter's apt; this comes after leaving WTC after reported 'medical episode.' pic.twitter.com/OQBpSNNNz6 — Fox News (@FoxNews) September 11, 2016

“It’s a beautiful day in New York,” Clinton told journalists waiting outside her daughter’s house, AP reports.

Clinton was attending the 9/11 memorial in New York on the 15th anniversary of the deadly attacks, which claimed nearly 3,000 lives.

The overwhelming majority of the victims died after two passenger planes slammed into the World Trade Center buildings in New York on September 11, 2001.