Democratic presidential candidate Bernie Sanders speaks at a campaign rally at Arizona Veterans Memorial Coliseum on March 5 in Phoenix.

PHOENIX — A man waving a Nazi flag and shouting “Heil Hitler” was kicked out of a rally for Bernie Sanders on Thursday, a shocking incident targeting the man running to be the first Jewish president.

The flag, styled professionally in the actual designs of Nazi Germany, hung prominently over a banister at the 7,000-person Arizona Veterans Memorial Coliseum at the start of Sanders’ speech. The person stationed himself in the upper deck of the arena, behind where Sanders was speaking.

The man was shouting anti-Jewish slurs at Sanders and performing the Nazi salute, said Ron Mack, 40, an attendee at the rally who was sitting nearby. “He never put his arm down,” Mack said. “Everybody was in disbelief.”

Security removed the man from the event several seconds after he unfurled the flag. Mack, who spoke to BuzzFeed News the day after the rally, followed him outside to make sure he was removed, and the man shouted racial slurs at him, an incident that was captured on video.

On Friday morning, taking questions at the Phoenix airport, Sanders told reporters that he was “shocked” to learn about the flag from his staff.

“I speak not only as a Jewish American — I think I can speak for the families of some 400,000 American troops who died fighting Nazism, fighting fascism — that it is horrific," he said. “It is beyond disgusting to see that, in the United States of America, there are people who would show the emblem of Hitler and Nazism.”

Sanders said that he has seen plenty of protesters at his events over the years — many of them Trump supporters — “but this was something different,” he said, describing the swastika as “unspeakable” and the “most detestable symbol in modern history.”

On Friday afternoon, in a tweet, Biden wrote of the display at the Friday rally, "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."

The Anti-Defamation League identified the man as Robert Sterkeson, a white supremacist who has "harassed a range of Jewish and Muslim organizations and events," often posting the stunts on YouTube.

Sanders appeared to hear the commotion, turning to his right to look to the stands, but the flag had already been taken down. Aides told him about the incident after the rally.

Multiple protesters caused disruptions at the rally, including one who unfurled a “TRUMP” banner.

Video and pictures of the incident spread on Instagram and Twitter.