"What about free speech? What about free speech," one of the protesters yelled Monday while being dragged out of the Westgate Resort & Casino on the Vegas strip.
A BuzzFeed reporter first posted a video clip of the encounter to Twitter that included a male voice saying "Light that motherf----- on fire," an account confirmed to CNN by a witness in Las Vegas.
One protester, Maria Hayden, provided a video to CNN of the exchange. Another, Missy Lane, said it was a Trump supporter who used those words. "It's like pure hate that comes out of people," she said. "It's unbelievable what he stirs up in people. It's sick."
CNN has reached out to the Trump campaign for comment Tuesday.
While having security staff remove protesters or hecklers from campaign events is commonplace for just about all candidates on the 2016 trail, Trump's security staffers are aggressive about removing demonstrators, who have become a frequent presence at Trump events.
Security guards removed several other protesters from Tuesday's rally as supporters chanted "Trump! Trump!"
Another protester, Alejandra Romero, said a security guard took her phone, threw it, and said, "You want your phone go get your phone."
Last month, a half dozen attendees at a Birmingham campaign rally shoved, tackled, punched and kicked a black protester who disrupted Trump's speech by chanting "Black Lives Matter!"
"Maybe he should have been roughed up because it was absolutely disgusting what he was doing," Trump said on Fox News following the incident, less than 24 hours after his campaign said it "does not condone" the physical altercation.
In rallies following the Birmingham event, Trump staff have asked supporters to not get physical with protesters, though that warning did not appear to be given before Monday night's gathering.