A chilling new video of the World Trade Center Towers collapsing on September 11, 2001, following terrorist suicide attacks, has surfaced online, shedding fresh light on one of the darkest days in American history.

Kei Sugimoto, a Japanese-American who was 24 years old at the time, has released a nearly 1-hour, never-before-seen video on his YouTube channel.

Sugimoto was a Mainframe Operator at the time at Nissho Iwai Shoji when the terrorist attacks occurred and filmed the footage from the roof of 64 St. Marks Place in New York City.

He used a Sony VX2000 with a teleconverter to capture the harrowing moments, according to his Youtube description.

On July 22, Sugimoto first released a six-minute video on his YouTube channel, revealing the footage for the first time.

In the video's description, Sugimoto wrote: "Footage I filmed of the World Trade Center Collapsing on 9/11/2001. Filmed from the roof of 64 St Marks Place in NYC on a Sony VX2000 with teleconverter. Upscaled to 4K 60p using Topaz Video AI. For historical archival purposes only."

When asked why he decided to release the footage after 23 years, Sugimoto explained, "I was cleaning my closet and found boxes full of Hi-8, Digital-8, and DV tapes."

"When trying to play them back, I noticed that maybe about a third of them had demagnetized over time and were either blank or suffering from major data corruption. After researching online, I learned that video tapes are not immune from age even when stored in ideal conditions, so I frantically started to digitize them. Thus, I'm just uploading the video now," he added.

The video was captured after two planes crashed into the World Trade Center.

"I saw the second plane crash but did not film it on camera. If I remember correctly, I think I ran to get my video camera after seeing the second plane crash, sensing that this was no ordinary accident," Sugimoto said.