AEW star Rey Fenix suffered a horrific arm injury in the middle of his match Wednesday night ... and -- **HUGE WARNING** -- the video of the incident is extremely graphic.
Fenix was wrestling against Jungle Boy and Luchasaurus in a tag-team event with his partner, Penta Zero Miedo, at AEW Dynamite ... when the gruesome injury occurred.
Luchasaurus slammed Fenix through a table -- and as the two wrestlers hit the ground, Fenix's arm got caught in an awkward position and snapped backward.
Fenix was in an extreme amount of pain -- video from the ringside angle shows he was screaming loudly after hurting the arm.