Politics Jill Biden Says She Worried About Her Flight Attendant Sister During 9/11: 'Scared to Death' "There were so many things swirling that day because I was worried about Joe's safety, but I just could not imagine that my sister was on one of those flights," Dr. Biden told the Associated Press By Virginia Chamlee Virginia Chamlee Politics Writer - PEOPLE People Editorial Guidelines Published on September 12, 2022 11:15 AM Share Tweet Pin Email First lady Jill Biden participates in a moment of silence with the members of the Association of Flight Attendants at the Flight 93 National Memorial Wall of Names following a ceremony commemorating the 21st anniversary of the Sept. 11, 2001 terrorist attacks in Shanksville, Pa., Sunday, Sept. 11, 2022. Photo: AP Photo/Barry Reeger As the news began breaking on Sept. 11, 2001 that four U.S. airplanes had been hijacked, Dr. Jill Biden says she was "scared to death" that her sister, who was then a flight attendant for United Airlines, may have been on one of the planes. "I didn't know where she was, whether she was flying, not flying, where she was," the first lady said of her sister, Bonny Jacobs, in a Saturday interview with the Associated Press. "And then I found out she was home." "I went straight to Bonny's house," she added. Jacobs was by Biden's side on Sunday, as the two marked the 21st anniversary of the terror attacks at the Flight 93 National Memorial in Shanksville, Pennsylvania. Speaking to AP, Jacobs said she had the day off on 9/11 — which began as an otherwise beautiful day. "So when I got up around noon, it was such a gorgeous day," Jacobs told the outlet. "I had my coffee. I sat outside. I literally said out loud, 'I'm doing nothing today. This day is gorgeous.'" Within hours, her sister had sent her a message, asking her to turn on the TV. Jill Biden Shares the Heartfelt Moment She Told Her Students Her Sister Had Cancer: 'I Needed Their Strength' "I started to shake," Jacobs said of learning about the hijackings. She spent the rest of the day glued to the news. "And then the first person that came to the house was Jill," Jacobs added in the interview. "I hadn't called her to come, but she just showed up, and she was there for me, as usual." Never miss a story — sign up for PEOPLE's free daily newsletter to stay up to date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories. Biden, meanwhile, described how she was on the phone with her husband, then-Sen. Joe Biden, as she watched another plane hit the second World Trade Center tower live. "There were so many things swirling that day because I was worried about Joe's safety, but I just could not imagine that my sister was on one of those flights," Biden told the outlet. "I don't know what word I want to use. I was so worried and I don't even think that's strong enough." President Joe Biden Delivers Moving Remarks at 9/11 Memorial Ceremony: 'The Grief Was So Raw' In prepared remarks delivered Sunday, Dr. Biden noted her sister's love of her job as a flight attendant — and the weight of the tragedy, on a personal level. "It's a job that she has loved for many years, and I knew that the weight of this tragedy would be heavier for her," Biden said. "When I got to her house, I realized that I was right. She hadn't just lost colleagues. She had lost friends."