Warning: Graphic content

https://twitter.com/feednewslive/status/751278935736930305

A video from Fox 4 News in Dallas shows one of the rifle-wielding snipers sneaking up on and shooting a police officer hiding behind a pillar outside a downtown skyscraper.

The video shows the rifle-wielding suspect running down a sidewalk in front of the well-lit commercial tower as the uniformed officer takes cover behind the pillar.

The shooter raises his long rifle just steps away from the officer and fires — and the officer collapses.