AceShowbiz - Katie Couric initially assumed the 9/11 terror atrocities were an "accident." The 66-year-old journalist, who reported the plane strikes as they unfolded to millions of "Today" show viewers 22 years ago has now recalled the shocking day by sharing footage of the on-air moment that she learned about the first plane crashing into the World Trade Center.

She said on Instagram on Monday, September 11 in a post to mark the 22nd anniversary of the worst terror outrage to hit U.S. soil, "We had no idea what was going on - and assumed it had just been an accident."

While on air on 11 September, 2001, Katie spoke to a woman named Jennifer Oberstein who told the anchor what she saw that horrifying morning. Katie recalled, "Jennifer proceeded to give us a play by play of what she saw, live on the air, and we were on the phone with her when she watched the second plane crash into the second tower. I'm forever grateful for her help reporting this story."

On the morning of Tuesday, 11 September 2001, 19 terrorists hijacked four commercial airliners scheduled to travel from the New England and Mid-Atlantic regions of the East Coast to California. The hijackers crashed the first two planes into the Twin Towers of the World Trade Center in New York City and aimed the next two flights toward targets in or near Washington D.C.

A third team of terrorists succeeded in crashing into the Pentagon, the headquarters of the U.S. Department of Defense in Arlington County, Virginia, while the fourth plane crashed in rural Pennsylvania following a passenger revolt.

The attacks killed almost 3,000 people and sparked the multi-decade "global war on terror."