More than 20 years after the tragic events of September 11, 2001, an astonishing new video of the 9/11 attack on the World Trade Center in New York has emerged online.

Kevin Westley shared the never-before-seen clip, which is nearly nine minutes long, on YouTube last week, and it has since been viewed over 522,000 times.

It depicts a previously unseen angle of the second plane striking the World Trade Center’s South Tower, seventeen minutes after American Airlines Flight 11 struck the North Tower.

The video was shot from a boat, with a crowd of stunned onlookers looking up at the towers.

The video camera then pans around at the two-minute mark to capture the second plane flying in over the water before colliding with the South Tower, eliciting screams of horror from the audience.

“Why did it take Kevin over 20 years to upload the best quality video of the 9/11 attacks?” one person wondered.

“I posted this video in the 2000s but accidentally left it private until now,” uploader Kevin Westley explained in a post alongside the video. “I noticed the video was private and decided to make it public.”

Kevin wrote a lengthy post about his experiences witnessing the horrific 9/11 attacks, as well as his subsequent tour of duty as an aircraft commander flying combat missions in the 2003 Iraq war.

“In an instant I saw 2,763 die. 25,000 injured,” he said, recalling the horror of the New York attacks.

“As I was caught in the dust cloud of the collapse, I remember seeing a picture of a child (and am now wondering) if I now was looking at an orphan.”