The Democratic presidential candidate and gun owner made the seemingly unguarded comment in an interview with Oprah Winfrey before a live studio audience on Thursday when the conversation turned to gun laws.
"I probably should not have said that. But my staff will deal with that later," Harris said, laughing.
Harris, who has robust protection from the US Secret Service, made the statement amid heightened concern about political violence after a second potential assassination attempt against her opponent in the November 5 presidential election, Republican and former president Donald Trump.
Trump favours few restrictions on arms and ammunition while Harris supports a ban on assault weapons, stricter background checks for gun buyers, and "red flag" laws that can temporarily take guns away from those deemed dangerous.
Harris told Winfrey she supported the Second Amendment to the United States Constitution, which protects the right to gun ownership.
Harris mentioned her gun ownership in 2019 when she was a US senator and again in last week's debate with Trump in what seemed like an appeal to more conservative voters.
Harris owns a handgun for personal safety reasons, and it is stowed away in a secure location at her California home, a White House source told Reuters earlier.
The source declined to identify the make of gun, but said it is the same gun Harris mentioned in 2019 on the campaign trail.
Harris, the former district attorney of San Francisco and California attorney general, told reporters in 2019: "I am a gun owner, and I own a gun for probably the reason a lot of people do - for personal safety. I was a career prosecutor."
One-third of Americans own a gun and about two-thirds of Americans support stricter gun laws overall, with nearly 90% supporting policies that would prevent mentally ill people from getting guns, Pew Research shows.
Star-studded event
The star-studded virtual event hosted by Winfrey to build enthusiasm for Harris' campaign was marked by teary moments and celebrity endorsements, drawing hundreds of thousands of viewers across social media.
Winfrey hosted the "Unite for America" event with activist group Win with Black Women, that aimed to register people to vote and bolster Harris in states such as Pennsylvania, Georgia and Michigan that are set to decide the election.
Shanette Williams, the mother of Amber Nicole Thurman, a 28-year old Georgia woman who died in August 2022 after a hospital treatment delay related to the state's restrictive abortion laws, told the audience: "You're looking at a mother that is broken, the worst pain ever that a mother, that a parent can ever feel."
Harris responded: "I'm just so sad. And the courage that you all have shown is extraordinary." Many in the studio audience of about 400 were in tears.
Natalie Griffith, a 15-year-old student from Apalachee High School in Georgia who was shot twice while in math class two weeks ago, sat with her parents in the front row.
“What are we doing?” asked Natalie’s mother, Marilda Griffith. “We have a job, that job is to protect our children. We have to stop it," she said, as she and some in the audience, virtual and in-person, cried.
Harris and Democrats have promised to restore national abortion rights impacted by a 2022 Supreme Court decision and pass a ban on assault weapons often used in mass shootings.
Celebrities including comedians Chris Rock and Ben Stiller along with actors Julia Roberts, Meryl Streep and Bryan Cranston joined the event and offered their reasons for backing Harris or peppered her with questions.
"I want to bring my daughters to the White House to meet this black woman president," Rock said.
Winfrey noted Harris' swift transformation after President Joe Biden stepped out of the race in late July, lauding Harris for "stepping into her power."
"You know we each have those moments in our lives when its time to step up," Harris said. Before Biden was forced out, Harris' strength as a presidential candidate was questioned by some Democrats in Washington, including Biden. But she has revived Democrats' chances, bringing in new fundraising and enthusiasm.
Harris campaign advisers say nearly 200,000 people signed up to watch the livestream, and its YouTube audience was nearly 100,000 by the end. Instagram, Facebook, Tiktok and Twitch accounts for both Winfrey and Harris also showed the event.
Dozens of grassroots groups including Latinas for Harris, White Dudes for Harris and Win With Black Men that held virtual organizing and fundraising calls in the days after Harris became the Democratic nominee and Thursday marked the first time they all joined in one event.
In a recent Reuters poll, Harris led Trump 47% to 42%.
Harris was ahead in the battleground states of Michigan, Pennsylvania, Wisconsin, Nevada and North Carolina, while Trump had greater support in Georgia, according to polling averages from aggregator FiveThirtyEight. They are tied in Arizona.