Chris Brown Fan Gets Knocked Unconscious During Fight at Concert

​A vicious fight broke out at a Chris Brown concert Friday ... and TMZ has obtained video of the VERY SCARY scene ... a woman laid out unconscious on the ground while two men are going at it around her.

Eyewitnesses tell TMZ ... the nasty brawl started between two women in the front section of the Kia Forum in Inglewood, CA, near the end of Breezy's set. Lil Baby also performed at the August 26 show.

Two men jumped into the fight ... and one of them clocked one of the women, knocking her unconscious.

Several fans dragged the woman to the side of the arena and tried to revive her, but she wouldn't move. The battle between the two men also spilled over to the side. Law enforcement sources tell us at least one person was transported to the hospital.

Our video shows the men wrestling and wildly throwing punches while the woman lays like a rag doll nearby with people standing over her.

We're told bystanders broke up the fight after about three minutes and security guards didn't do much at all when they finally arrived on the scene.

The condition of the injured woman is unknown. It's also unclear what precipitated the fight or how the parties knew each other ... if it all.

As for Breezy, he didn't seem to know what was going down and continued his performance.

We've reached out to police and EMS ... so far no word back.