On Friday, Sen. Bernie Sanders (I-VT), who is the only Jewish candidate in the 2020 presidential race, slammed the heckler who unfurled a Nazi flag at his campaign rally in Phoenix, Arizona the previous night.

“As someone whose family was wiped out by Hitler and as an American, to have in this country somebody bringing forth the most detestable symbol in modern history is unspeakable,” Sanders tweeted with a video of him commenting on the incident in a press conference.

“I will simply say this, and I speak not only as a Jewish-American, I think I can speak for the families of some four hundred thousand American troops who died fighting Nazism, fighting fascism, that it is horrific,” the Vermont senator told reporters.

A video posted by a rally attendee shows a man in a white shirt waving a swastika flag before Sanders supporters ripped it away from his hands and the police escorted him out. BuzzFeed News reported that the man had also shouted anti-Semitic slurs.

Sanders did not see the flag at that moment. “I was shocked to learn about that later,” he said during the press conference on Friday.

As the man who had waved the flag was walking away from the arena outside, he yelled “Shut up, [n-word]” at a black man, a video posted by ABC 15 Arizona shows.

Joe Biden, the other top contender in the Democratic primary race, defended his rival on Friday.

“I don’t care who you’re supporting, attacks like this against a man who could be the first Jewish President are disgusting and beyond the pale,” he tweeted. “Hatred and bigotry have no place in America — and it’s up to all of us to root out these evils wherever they’re found.”

During the same Sanders rally, several supporters of President Donald Trump waved a flag emblazoned with Trump’s name and his “Keep America Great” campaign slogan, per a video posted by local KOLD News 13 reporter Melissa Egan. They were also kicked out by the police.

The Anti-Defamation League, a Jewish advocacy organization, believes it has identified the person responsible for the Nazi flag, but TPM could not independently verify the allegation.

The Phoenix Police Department did not respond to TPM’s request for comment.