Transportation Secretary Elaine Chao, who has served in the Trump administration since 2017, announced her resignation on Thursday, the first member of Trump's cabinet to resign in the wake of the deadly riot at the U.S. Capitol on Wednesday.

"It has been the honor of a lifetime to serve the U.S. Department of Transportation," Chao wrote on Twitter. Her resignation will be effective Jan. 11.

Chao was previously Secretary of Labor under President George W. Bush for the entirety of his two terms in the White House. She is also married to Senate Majority Leader Mitch McConnel (R-KY).

In an email to her Department of Transportation colleagues obtained by Spectrum News, Chao said that she was "deeply troubled" and "simply cannot set aside" by violent protesters loyal to President Donald Trump storming the U.S. Capitol on Wednesday in a brazen attempt to overturn the results of America’s presidential election.

"I am tremendously proud of the many accomplishments we were able to achieve together for our country," she wrote in her note to her colleagues.

Chao committed to helping the transition to President-elect Joe Biden's nominee to be her successor, Pete Buttigieg.

Chao previously served as Deputy Secretary of Transportation under President George H.W. Bush. Chao was born in Taipei, Taiwan, and attended Syosset High School on Long Island in New York before attending Mount Holyoke College and Harvard Business School.

While Chao is the first Cabinet official to resign, she joins a growing list of other Trump administration members to resign in response to the unrest at the U.S. Capitol, including Mick Mulvaney.

Mulvaney told CNBC on Thursday morning that he has stepped down as special envoy to Northern Ireland. He was President Donald Trump’s chief of staff from January 2019 to March 2020.

“I called [Secretary of State] Mike Pompeo last night to let him know I was resigning from that. I can’t do it. I can’t stay,” Mulvaney said in an interview on “Squawk Box.”

“We didn’t sign up for what you saw last night,” he added. “We signed up for making America great again. We signed up for lower taxes and less regulation. The president has a long list of successes that we can be proud of, but all of that went away yesterday.”

Mulvaney said Trump is “not the same as he was eight months ago.”

A handful of other Trump administration officials and aides have also announced their resignations, and others reportedly are considering doing the same.

“Those who choose to stay — and I have talked with some of them — are choosing to stay because they’re worried the president might put someone worse in,” Mulvaney said. 

Some aides also plan to stay until Jan. 20 to help ensure a smooth transition to the Biden administration, The Associated Press reported.

Other officials who have resigned are Stephanie Grisham, chief of staff to first lady Melania Trump and a former White House press secretary; Deputy National Security Adviser Matt Pottinger, Deputy Press Secretary Sarah Matthews and White House social secretary Rickie Niceta. Ryan Tully also resigned from the National Security Council, Bloomberg reported Thursday.

The exodus comes after a mob of pro-Trump protesters stormed the Capitol Wednesday as Congress convened to certify Joe Biden’s win in the Electoral College. 

Just before, Trump, who has falsely claimed widespread voter fraud cost him the election, and his allies addressed the president’s supporters at a nearby rally. Trump said, “You will never take back our country with weakness,” and called on the protesters to march to the Capitol. The president’s attorney, Rudy Giuliani, told the crowd, “Let's have trial by combat.”

Trump initially remained silent as protesters damaged property at the Capitol and forced lawmakers to be escorted to secure locations, halting their proceedings for nearly six hours. A woman was fatally shot by Capitol Police in the melee, and three other people died from medical emergencies, authorities said.

On Twitter, the president eventually called for peace and told the protesters it was time to go home. But he also seemed to excuse their actions by saying, in a post deleted by Twitter, “These are the things and events that happen when a sacred landslide election victory is so unceremoniously & viciously stripped away from great patriots who have been badly & unfairly treated for so long.” In a video, also now deleted, the president told the protesters, “We love you.”

According to multiple reports, National Security Adviser Robert O’Brien also was considering resigning, but an official told Reuters that O’Brien has no plans to quit.

White House Deputy Chief of Staff Chris Liddell and Transportation Secretary Elaine Chao are among other officials who are mulling turning in their resignations, according to reports.

Grisham did not mention the unrest in a tweet announcing her resignation, but Reuters reported that Wednesday’s events prompted her exit. 

“It has been an honor to serve the country in the @WhiteHouse,” Grisham tweeted. “I am very proud to have been a part of @FLOTUS @MELANIATRUMP mission to help children everywhere, & proud of the many accomplishments of this Administration.”

Matthews said in a statement she was “distrubed” by Wednesday’s events.

"I was honored to serve in the Trump administration and proud of the policies we enacted,” she said. “As someone who worked in the halls of Congress I was deeply disturbed by what I saw today. I'll be stepping down from my role, effective immediately. Our nation needs a peaceful transfer of power."

Pottinger was a key figure in the development of Trump’s China policy. Tully was the top Europe and Russia official on the NSC. Niceta oversaw all White House events, including state visits and annual holiday festivities.