Washington (CNN) Sen. Bernie Sanders said Sunday that he "never expected in (his) life as an American" to see a Nazi flag waved at a major political rally, several days after a man unfurled one during a speech the Democratic presidential candidate gave at an event in Arizona.

In an interview with CNN's Jake Tapper on "State of the Union," Sanders called the incident "unspeakable" and "disgusting."

"Obviously, it is unspeakable. It is disgusting. It is something -- I got to tell you, I never expected in my life, as an American, to see a swastika at a major political rally. It's horrible," the Vermont senator said.

On Thursday, a man was kicked out of a Sanders rally after he unfurled a flag with a swastika on it. The man was immediately booed by the crowd. Members of the audience ripped the flag from the individual's hand, and the individual was quickly removed by security.

The incident, which Sanders said on Sunday he learned about after leaving the stage, sparked an outcry, was widely denounced on social media and prompted calls for security.

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