Teenager is shot dead for arguing with a stranger who disrespected his girlfriend and it was livestreamed

Another silly, senseless killing has been carried out in the US and it was livestreamed, as it is becoming the norm.  The disturbing video shows a young man lying in a pool of his blood in Brooklyn, New York.

He had reportedly been trying to save a woman from her abusive boyfriend.
According to witnesses, the deceased got into an argument with the man over the way he was disrespecting his girlfriend but the man was not having it and in a flash, he brought out a gun and fired two shots. 

In the video, a woman can be seen screaming for spectators to do something but no one moved as they informed her that nothing could be done. 

"Does anybody know how to do CPR?" the woman asked, crying. 

"Miss, trust me, trust me, miss, he can't breathe right now. He's gone," voices replied in the background.

Police officers arrived soon after that and everyone except the lady gave way.

See the video below.