NASA astronaut Frank Culbertson was the only American not on Earth when the 9/11 terrorist attacks happened 10 years ago, He was on board the International Space Station and filmed the shocking incident.

Culbertson told NASA he was relaxing with a Tom Clancy novel when he heard reports of the attacks on New York. He said the wall between the events in the book and the real world seemed to collapse. Culbertson soon learned that what he was seeing wasn't fiction.

The space station passed over the U.S. East Coast when the incident happened and Culbertson and his colleagues had a huge vantage point.

Once I saw it out the window, we took video as the second tower was collapsing, he said. I didn't know exactly what was happening, but I knew it was really bad because there was a big cloud of debris covering Manhattan. That's when it really became painful because it was like seeing a wound in the side of your country.

The smoke seemed to have an odd bloom to it at the base of the column that was streaming south of the city, Culbertson wrote in a letter detailing the event the next day.

See a portion of NASA's video below: