Multiple independent fact-checkers cast doubt on real-estate tycoon Donald Trump's claims over the weekend that he saw people "cheering" in New Jersey after the September 11, 2001, terrorist attacks on US soil.

In an interview with ABC on Sunday, Trump stood by claims first made at a Saturday rally that he saw people in New Jersey — which Trump noted has "large Arab populations" — cheering after the attacks brought down the World Trade Center in lower Manhattan.

"There were people that were cheering on the other side of New Jersey, where you have large Arab populations," Trump said Sunday. "They were cheering as the World Trade Center came down. I know it might be not politically correct for you to talk about it, but there were people cheering as that building came down — as those buildings came down. And that tells you something. It was well covered at the time."

Despite Trump's insistence that he saw such celebrations, political fact-checkers across the board have found little to no evidence of any public celebrations after the attacks.

PolitiFact noted that there were several media reports of police inquiries into individuals who were suspected of celebrating the attacks in Jersey City and nearby Paterson, but there is no evidence that these investigations revealed any actual celebrations or resulted in any convictions.

"This defies basic logic," PolitiFact's Lauren Carroll wrote in a "Pants on Fire" ruling.

"If thousands and thousands of people were celebrating the 9/11 attacks on American soil, many people beyond Trump would remember it," Carroll continued. "And in the 21st century, there would be video or visual evidence."

The New York Times said "no news reports exist of people celebrating."

And The Washington Post reached the same conclusion, citing a strongly worded rebuttal of Trump's comments by the then-police commissioner of Paterson.

"Trump has defamed the Muslim communities of New Jersey," Post fact-checker Glenn Kessler wrote. "He cannot simply assert something so damning; he must provide some real evidence or else issue an apology."

Trump, for his part, defended himself again on Monday — and demanded an apology from everyone who had called him wrong. On his Twitter feed, he pointed to a Washington Post story from September 18, 2001:

The fact checks addressed that Post story. PolitiFact wrote that it "found no evidence that any of these allegations ever stuck."

The Post, for its part, noted that Trump claimed he saw "thousands" of people celebrating and watched it unfold on television, a scene the piece did not describe. Kessler, the Post's fact-checker, also spoke to one of the 2001 story's reporters, who said it was unclear whether those allegations were ever confirmed.

"I certainly do not remember anyone saying that thousands or even hundreds of people were celebrating," Serge Kolvaleski, one of the reporters, told The Post. “That was not the case, as best as I can remember.”​

Other New Jersey public officials have taken issue with Trump's claims.

On Sunday, Mayor Steve Fulop of Jersey City (D) slammed Trump, denying that anyone had cheered in Jersey City after the attacks.

"Trump is plain wrong, and he is shamefully politicizing an emotionally charged issue," Fulop said in a statement. "No one in Jersey City cheered on September 11."

Gov. Chris Christie of New Jersey. AP Photo/Nati Harnik Though his denial of Trump's charges was less terse, Gov. Chris Christie of New Jersey, one of Trump's Republican presidential rivals, also cast doubt on the real-estate magnate's claims.

"I don't recall that," Christie told a reporter, according to BuzzFeed. "I don't. I mean, listen, I can't say, Matt, I can't say that I have — 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 added: "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."

Many media organizations have appeared exasperated recently by Trump's repeated dismissal of facts.

The Washington Post noted that Trump had gotten more "four Pinocchio" ratings by its fact-checking than any other candidate in the 2016 race. And in a morning newsletter cowritten by "Meet the Press" host Chuck Todd on Monday, NBC News labeled Trump the first "post-truth" candidate.

"It's hard to disagree with the assessment of our colleague Benjy Sarlin," the authors wrote. "'Let's not sugarcoat what's going on. The GOP front-runner is spreading hateful falsehoods about blacks and Muslims.'"