First Lady Jill Biden is remembering September 11, 2001 - a day that not only changed the United States, but the world.
On the 20th anniversary of one of the darkest days in history, Dr. Biden, 70, reflected on 9/11.
"At 8:46 AM ET, on September 11, 2001, our memories split into 'before' and 'after.' That moment changed us all in some way," she told People.
"Twenty years ago today, in our shared experience of shock, grief, and resolve, we found unity. We leaned on each other, realizing we are stronger together than apart," she added.
She went on: "It can be difficult to untangle meaning from loss and tragedy, when nothing seems clear and we just want one more minute of the 'before' again. Our feelings never follow a straight line.
"Yet, as we remember those we lost because of the September 11th attacks, and contemplate our changed world since, may we honor their lives and legacies by reaching out for each other again in unity, recognizing that our similarities are infinite and our differences precious," she added in a statement to People.
Recalling how her day started, Dr Biden said she went off on a run. Remembering it as a quiet early morning, her husband Joe Biden - then a senator of Delaware - was commuting to Washington, DC, and their daughter Ashley was away at college.
She was preparing to teach an English class at Delaware Technical Community College when she first saw news coverage that a plane had crashed into the North Tower of the World Trade Center.
Dr. Biden then immediately called her husband, who was not aware of what was taking place in New York City at the time as he was on an Amtrak train, according to Associated Press.
"Oh my God. Oh my God. Oh my God," she reportedly cried on the phone as the second tower was hit.
Shaken from what she had just witnessed, she went to work, only to find students and faculty members in the same distressed state.
When Dr. Biden ended her class and drove to check on her younger sister Bonnie - who was a flight attendant at the time and knew several of the crew members who worked on the United flight that crashed in Shanksville, Pennsylvania - she was greeted by an equally emotional sibling.