SALT LAKE CITY — One of the defining moments of Thursday night’s Democratic debate came during the second hour in a fiery exchange between California Sen. Kamala Harris and former Vice President Joe Biden.

Harris pushed Biden “to answer for his role in legislation that criminal justice experts say helped lay the groundwork for the mass incarceration that has devastated America’s black communities,” according to The New York Times.

Watch the moment below:

Harris said to Biden, "I do not believe you are a racist and I agree with you when you commit yourself to ... finding common ground. But it was personal and actually very hurtful to hear you talk about the reputations of two senators who built their careers on segregation of race.”

Harris asked Biden whether he agreed that he was wrong to oppose busing in America.

"I did not oppose busing in America. I opposed busing by the department of education,” Biden said.

Harris replied, "...But that is where the federal government must step in."

Twitter reacted to the moment.