Ben Carson 'Doesn't Stand Behind' His Own Remarks About American Muslims Cheering on 9/11

—PAHRUMP, Nevada -- Hours after telling reporters that he saw a video of American Muslims in New Jersey cheering on Sept. 11, 2001, when the World Trade Center's twin towers fell, Ben Carson's campaign apologized for the remarks, saying he "doesn't stand behind" them and that they were "a mistake."

When asked by ABC News if American Muslims were cheering on 9/11 -- as has been suggested by Donald Trump -- Carson said “Yes.”

“I saw the film of it, yeah,” he said and cited "the newsreels" of 9/11 coverage at the time.

However, Carson made a 180 a short time later.

"He doesn't stand behind his comments to New Jersey and American Muslims," said campaign spokesman Doug Watts said. "He was rather thinking of the protests going on in the Middle East and some of the demonstrations that we're going on in celebration of the towers going down.

"He doesn't stand behind his references and apologizes for the mistaken references. It was a mistake on his part and he clearly wasn't really thinking about New Jersey, he was thinking about the Middle East."

Over the weekend, fellow GOP candidate Trump said he saw New Jersey residents celebrating the 9/11 terrorist attacks -- a claim that has been challenged by fact checkers.

“I watched in Jersey City, New Jersey, where thousands and thousands of people were cheering as that building was coming down,” he said in a speech on Saturday. “Thousands of people were cheering.”

Trump repeated the assertion to ABC’s George Stephanopoulos on “This Week."

“It was well covered at the time, George,” Trump said Sunday. “There were people over in New Jersey that were watching it, a heavy Arab population, that were cheering as the buildings came down.”

The Washington Post called the claim “outrageous” and the independent fact-checking website, PolitiFact, concluded that Trump’s statement “flies in the face of all the evidence we could find. We rate this statement 'Pants on Fire.'”

On Monday, Trump tweeted a link to a Sept. 18, 2001, Washington Post story:

But The Post's fact-checker refuted the notion that the reported allegations in the story back up Trump’s claim.

Former New York governor and GOP presidential candidate George Pataki denounced Trump's claim on Twitter.

Jersey City, N.J., Mayor Steven Fulop also weighed in on Twitter.

Sen. Marco Rubio addressed Trump's claim today in Iowa.

"It's not true. And there's plenty of fact-checks to prove that it isn't," he said.

N.J. Gov. Chris Christie, in an interview on Sunday, said he "didn't recall" Muslims cheering in the streets on 9/11.

"It was a pretty emotional time for me because, as I’ve mentioned before, there’s family involved, there’s friends involved and so it was a pretty harrowing time," he said. "I do not remember that. And so, it’s not something that was part of my recollection. I think if it had happened, I would remember it. But, you know, there could be things I forget, too. I don’t remember that. No."

ABC News' Ryan Struyk contributed to this report.

Get real-time updates as this story unfolds. To start, just "star" this story in ABC News' phone app. Download ABC News for iPhone here or ABC News for Android here.