WTC Attack September 11, 2001 from New York Police Helicopter

A newly released video shows the Sept. 11 World Trade Center attack from the vantage point of a NYPD helicopter.

According to Gawker, the National Institute of Standards and Technology requested the 17-minute video through the Freedom of Information Act, and the video was sent anonymously to the secret-sharing website Cryptome, which posted it. The Institute investigated the 9/11 attacks.

A warning to readers: The video, posted below, is difficult to watch--and voices on the soundtrack can be heard cursing as the horrific attack unfolds.