Sen. Claire McCaskill Claire Conner McCaskillDemocratic-linked group runs ads in Kansas GOP Senate primary Trump mocked for low attendance at rally Missouri county issues travel advisory for Lake of the Ozarks after Memorial Day parties MORE (D-Mo.) says she is appalled by protesters responding destructively to President Trump’s inauguration Friday.

McCaskill tweeted shortly after Washington, D.C., police announced that they had arrested "numerous" people for destructively protesting against Trump.

“Nothing is more un-American than protesters who are not peaceful – disgusting,” tweeted McCaskill, who backed 2016 Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonHillicon Valley: FBI chief says Russia is trying to interfere in election to undermine Biden | Treasury Dept. sanctions Iranian government-backed hackers The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters FBI chief says Russia is trying to interfere in election to undermine Biden MORE over Trump.

“I understand the angst out there today for all of you throwing stuff at me,” she added. "Sorry, but I believe peaceful protest is always the right way.”

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McCaskill also said violent protests run counter to the teachings of civil rights leaders, adding they discredit peaceful demonstrations as well.

“MLK and John Lewis were and are the role models for peaceful protest,” she wrote, referring to Martin Luther King Jr. and the Democratic representative from Georgia who recently said Trump was not a "legitimate" president, respectively. "But the small group will get all the attention – sigh."

Authorities told The Associated Press that those arrested were charged with rioting following incidents involving a group of about 100 people.

The demonstrators damaged vehicles, destroyed property and set small fires while armed with crowbars and hammers, officials added.

McCaskill is facing reelection in Missouri in 2018, a state Trump won by about 19 points over Clinton.

Trump took the oath of office Friday, making him America’s 45th president after a bitter White House race.

“We are transferring power from Washington, D.C., and giving it back to you, the people,” Trump said on the National Mall in Washington, D.C. "From this moment on, it’s going to be America first. I will fight for you with every breath in my body, and I will never, ever let you down.”

The unrest in D.C. was not the only tension nationwide, with spirited anti-Trump protests also erupting in cities ranging from New York City to San Francisco.