Hillary Clinton's spokesman was unable to say Monday whether he knew if the Democratic candidate passed out this weekend as she abruptly exited a 9/11 memorial service in New York City.

MSNBC's Andrea Mitchell asked Brian Fallon about a moment when Clinton was seen collapsing Sunday, knees buckling, as her aides helped her get into a van.

"Let me ask a couple of questions," Mitchell said. "Did [Clinton] ever lose consciousness?

"No, Andrea, I don't think so," the Clinton campaign spokesman said. "What I think happened — and I have no basis to question the veracity of the footage played — but from those there, I believe she was feeling hot which a lot of the other attendees described also feeling."

The Clinton campaign revealed after Clinton's fainting incident Sunday that she was diagnosed last week with pneumonia. Her team only admitted this after it claimed first that Clinton had merely "overheated" at the memorial event.

Clinton's campaign also only admitted this after she disappeared for 90 minutes Sunday, leaving the press totally in the dark as to her whereabouts.

Fallon continued Monday, saying, "I saw [Sen. Chuck Schumer, D-N.Y.,] and [Rep. Joe Crowley, D-N.Y.] also describe that it was a hot environment with all the people there for the ceremony."

"She left on her own accord. I think that as she was getting into the vehicle she got a little bit dizzy, and she was helped into the vehicle but immediately upon being seated there she was talking to staff and, like I said, making calls," he said.

The dizzy spell soon subsisted, he said, and alleged the Democratic nominee "was up running around in her daughter's apartment, chasing her grandkids around."

Fallon added, "Within 90 minutes, people saw her on the sidewalk as she exited her daughter's apartment building."

The Clinton campaign has already canceled her scheduled appearances this week in California.