An MMA fighter knocked out his opponent with an 'illegal and vicious' flying knee to the skull when he was already down

• Two athletes at a regional MMA show in South Dakota caught the attention of the global fight media after a knockout one journalist described as "illegal and vicious."
• With the fighter Boston Salmon already falling to the floor, his opponent, Shawn West, took a run at him and threw a flying knee to his skull.
• The unconscious fighter, who was bleeding heavily from the head, won by disqualification.
• You can watch the footage below. WARNING: Viewer discretion is advised.

An MMA show Friday contained a kneecap strike to the skull of an already downed opponent, a blow that one journalist described as "illegal and vicious" and that resulted in a disqualification win for the unconscious fighter.

Two American athletes, Boston Salmon and Shawn West, were competing at the Legacy Fighting Alliance 84 show in the state of South Dakota.

In the second round, both men landed right-hook punches so powerful they took backward steps to regain their composure.

West regained his balance, while Salmon fell to the floor.

In an apparent attempt to secure a conclusive finish, West ran at Salmon and hit him with a flying knee when he was already down.

The strike, illegal in mixed martial arts, left Salmon motionless on the canvas, bleeding from the head.

You can watch the footage below.

WARNING: Viewer discretion is advised.

The move horrified MMA media.

The prominent ESPN MMA journalist Ariel Helwani tweeted: "It doesn't get more illegal and vicious than this."

Salmon, unconscious, won the fight by disqualification.

• Read more:
• The UFC gave a Brit a $50,000 bonus after he overcame a fractured jaw and broken nose to KO his opponent
• A fighter scored a highlight-reel KO on his UFC debut and is now already targeting the title
• Kamaru Usman would welcome a 'crazy fight' with Georges St. Pierre after he dominated Jorge Masvidal on 'Fight Island'
• An MMA referee is facing backlash after letting a UFC veteran take a prolonged, hard-to-watch, completely unnecessary beating
• Kamaru Usman dominated Jorge Masvidal using foot stomps, grappling against the fence, and smothering on the mat