"They had bombs on the floor," Trump said. "Many people saw this, many, many people. Muslims living with them, in the same area, they saw that house."

Darren Hauck / Getty Images

Republican presidential frontrunner Donald Trump said Tuesday that Muslims knew a radicalized couple planned to launch the December terrorist attack on a county workers' holiday party in San Bernardino, California, but refused to notify authorities. Trump has repeated the claim to thousands of supporters at campaign rallies and, most recently, on live television during a presidential town hall interview on CNN. "In San Bernardino people knew what was going on," Trump told Anderson Cooper on Tuesday. "They had bombs on the floor. Many people saw this, many, many people. Muslims living with them, in the same area, they saw that house. They saw that." There is, however, no evidence to suggest this claim is true. Reports that neighbors saw suspicious activity at the Redlands home of Syed Farook and Tashfeen Malik, the radicalized couple behind the attack, but did nothing to stop it has been repeated in conservative media since the December assault, often arguing that political correctness and fear of racial profiling allowed the attack to happen. Those news reports all appear to stem from local media interviews with an unnamed man who said he was working in the neighborhood, and another man who was visiting the area and relaying, second-hand, a story from a neighbor. Neither mentioned "bombs" or any objects "on the floor."

Robyn Beck / AFP / Getty Images FBI agents investigate the Redlands, California, town home belonging to the attackers.

On Tuesday, Trump claimed a person "saw bombs all over the apartment," but didn't report the couple to police because they didn't "want to be accused of racial profiling." His comments came in response to a question from an audience-member about what he would do as president to protect the rights of minorities. Trump's answer, however, was more of an explanation as to why he would support "monitoring" Muslim communities and mosques, The candidate also appeared to go further than he previously had with the claim, suggesting it was not just neighbors who feared being accused of racial profiling, but other Muslims who decided to keep quiet about the pending attack. "He saw bombs all over the apartment, OK?" Trump told Cooper. "It's just an excuse. it's an illegal excuse." The Trump campaign did not respond to questions from BuzzFeed News about his claims and it is unclear where his assertion originated.

CBS Los Angeles / Via losangeles.cbslocal.com

In a CBS Los Angeles report in December, an unidentified man said he was working in the area and noticed some "unusual activity" but did not report it to law enforcement because, the reporter said, "he didn't want to be seen as racial profiling." The suspicious activity? Middle Eastern-looking men eating lunch together. "We noticed one day like six Middle Eastern guys walking by across the street, kinda dressed nice, and they were walking around and going to State Street and eat there, 'cus I see them eat there one day," the man said. "We sat around lunch thinking, 'Wow, what are those guys doing in this neighborhood.'"

Another visitor to the neighborhood, identified as Aaron Elswick, told KTLA that a neighbor said she saw suspicious activity as well, but didn't want to racially profile. Yet the second-hand information Elswick relayed hardly pointed to an upcoming terrorist attack. "They received quite a number of packages, and they were also working a lot in the garage," Elswick quoted the unnamed neighbor as saying. "I guess she didn't do anything, it sounds like she didn't do anything about it, she didn't want to do any kind of racial profiling." Like the other witness, there was no indication of bombs or Muslims being unwilling to relay that information to law enforcement, as Trump has suggested.

U.S. Customs and Border Protection via AP Tashfeen Malik and Syed Farook.

In the days following the attacks, Trump noted the local reports, telling reporters in Spencer, Iowa, that "it should not be racial profiling. They thought something bad was going on and didn't report it. Not good." At the time, Trump made no mention of other Muslims having advance knowledge of the attack. Instead, he focused on fears that racial profiling kept people from coming forward. But by late December, in Nashua, New Hampshire, Trump upped the ante and started referring to it as, "the Muslim situation." "We have Muslims — they're wonderful, we have wonderful people. But there's something going on there. They have to turn in, like for instance, these people in California, people knew he had bombs all over the floor, people knew it, why didn't they turn him in?" Trump told a rally. "You got to turn 'em in. Because it's their culture, they're around each other, they knew each other."

Nam Y. Huh / AP

Trump has also alleged that the couple's family, including Farook's sister and mother, "knew what was going on." "I think his mother knew what was going on. Anyone that went into the house, into the apartment, knew what was going on," he said in December. "They didn't tell the authorities. They knew what was going, the mother knew. I think the sister interviewed, I think she knew. We better get a little tough or a little smart or we're in trouble." But Farook's sister and brother-in-law told ABC News that the revelation Farook and Malik had pledged support to ISIS online was "shocking," and that Malik had "never mentioned any political thing." The family's attorney also said none of the family members were aware the two had become radicalized. In a statement to BuzzFeed News, FBI officials said investigators have interviewed more than 100 people in relation to the attack, but could not release any information because of the ongoing investigation.

Jae C. Hong / AP The garage door of the townhouse rented by the San Bernardino attackers Syed Farook and his wife, Tashfeen Malik.