[VIDEO IN EXTENDED ARTICLE]

It’s a heart-breaking bird’s eye view of New York’s darkest day.

As we mark a decade after the 9/11 attacks, a powerful 17-minute video taken from an NYPD helicopter on that fateful day surfaced on the Web not long ago.

Obtained by the National Institute of Standards and Technology, the leaked footage from inside the chopper shows the twin towers engulfed in clouds of smoke – and captures the stunned reactions of the cops when they fell.

Earlier in the footage, the officers take in a panoramic view of the unfolding pandemonium – and get perilously close to the black roiling smoke.

When the chopper briefly touches down in a nearby park, stunned officers gaze up at one of the burning towers. The video then shows the chopper back in the sky – and the aftermath of the now-fallen tower.

Click HERE to watch this video from a mobile device.

(Source: NY Daily News)