WASHINGTON—In a damning report that raised pointed questions about the federal agency’s security procedures, an investigation by the House Committee on Homeland Security concluded Monday that the Secret Service failed to account for the nation’s 393 million civilian-owned guns while protecting former President Donald Trump. “Despite countless past warnings, the Secret Service failed to heed the real threat posed to the former president by the hundreds of millions of firearms in the hands of everyday Americans,” said Rep. Mark Green (R-TN), the committee’s chair, who called upon Secret Service Director Kimberly Cheatle to resign due to her “shocking negligence” in failing to address decades of evidence pointing to a dramatic rise in the number of rifles, pistols, and shotguns in circulation around the country. “The Secret Service’s singular duty at that rally was to safeguard the president—it’s a duty they simply did not take seriously when you consider there’s a gun in this country for every U.S. resident. The seriousness of this lapse can’t be overstated.” Turner added that most unfortunate of all was the likelihood that violence against elected officials would only grow worse until the Secret Service started taking the dangers of guns seriously.