US transportation secretary Elaine Chao has announced her resignation, to take effect on Monday.
She criticised president Donald Trump's role in the events this week which saw his supporters storm the Capitol building in Washington, DC.
One protester was shot dead, three others died during the violence and a Capitol policeman has subsequently died of his injuries.
Chao was due to have been replaced on 20 January anyway by president-elect Joe Biden's pick for the role, Pete Buttigieg.
But in a statement addressed to 'Department of Transportation colleagues' yesterday, she said
"Our country experienced a traumatic and entirely avoidable event as supporters of the President stormed the Capitol building following a rally he addressed."
"As I'm sure is the case with many of you, it has deeply troubled me in a way that I simply cannot set aside."
Chao continued that she was "tremendously proud of the many accomplishments were were able to achieve together" and added that help will be extended to Buttigieg as he takes over "the responsibility of running this wonderful department".
Chao is married to the Senate majority leader, Republican Mitch McConnell,