Young Scooter died last week on his 39th birthday fleeing from cops -- and we now have more insight as to why ... through a very suspicious 911 call.

Today, Atlanta police released the audio that summoned them to William Nye Drive on Friday, where an unnamed woman made several disturbing claims about what she observed outside the residence.

The female caller told cops she witnessed a naked woman being dragged out of the house in a dispute over drugs -- saying the unclothed woman eventually called more men over to shoot the place up.

The caller -- claiming to be "the neighborhood watch" -- added she had long suspected the residence was a staging ground for either a drug-dealing or prostitution ring, and urged officers to hurry because the woman was "bleeding profusely" from her head while being held hostage.

There was also supposedly a child in danger -- but when Atlanta police rushed the scene, they encountered NONE OF THAT ... only someone who slammed the door in officers' faces when they approached the front.

It was then Young Scooter, likely clueless to the 911 dispatch, fled from the back of the residence with another man ... only to tear a femoral artery by jumping a fence as cops gave chase.

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Officers never discovered a woman "bleeding profusely" ... and Scooter eventually succumbed to his injuries at the Grady Marcus Trauma Center later that night.

Scooter's death sent shockwaves throughout the hip hop community and police are actively looking for the woman who made the bogus 911 call.