A video of the Sept 11 attacks on World Trade Centre has surfaced, which is shot from a police helicopter hovering near the burning World Trade Center towers in the hope of rescuing survivors.

The footage was obtained by The National Institute of Standards and Technology under the Freedom of Information Act as a part of their investigation into 9/11.

The whole tower, it's gone, one officer is heard yelling. Holy crap, they knocked the whole fricking thing down.

An officer wonders, How could it go down?

The 17 minutes of footage shot from a New York Police Department air and sea rescue chopper shows burning towers and captures the resultant collapse.

The video was released by NIST on March 3 under a Freedom of Information Act request, but it wasn't clear who published the footage online.

NIST investigated the collapse of the twin towers and another building that was part of the World Trade Center complex after the 2001 terror attacks.