US Secret Service Director Kimberly Cheatle said Monday “the buck stops with me” as questions have swirled about the agency’s security preparations following the assassination attempt on former President Donald Trump Saturday.

       Cheatle told ABC News on Monday that “the Secret Service is responsible for the protection of the former president” and “the buck stops with me, I am the director of the Secret Service.” She says she plans to stay on as director.

       The director said the shooting “was unacceptable,” adding, “This is an event that never should have happened.”

       When asked what her initial reaction was to the failed attempt on Trump’s life, Cheatle said: “Shock and then concern, obviously, for the former president.”

       In her first public comment since the Trump assassination attempt, Cheatle said in a statement earlier Monday the agency will “participate fully” in an independent review ordered by President Joe Biden and will work with Congress on “any oversight action.”

       Cheatle, who was appointed by Biden in 2022, expressed confidence in the agency’s security plan for this week’s Republican National Convention in Milwaukee and said changes have been made to Trump’s security detail since Saturday.

       “The Secret Service is tasked with the tremendous responsibility of protecting the current and former leaders of our democracy,” Cheatle said. “It is a responsibility that I take incredibly seriously, and I am committed to fulfilling that mission.”

       House Oversight Committee Republicans sent a letter to Cheatle with a new series of document requests and a notice to preserve all documents and communications regarding Trump’s Butler, Pennsylvania, rally, as the committee separately investigates the assassination attempt.

       CNN’s Annie Grayer and Whitney Wild contributed to this report.