While performing at the Louder Than Life festival on Saturday (Sept. 25), Machine Gun Kelly was consistently booed by the fans in attendance, which culminated in the rapper turned pop-punk rocker punching a fan who had broken past the barricade as security worked to restrain the musician.

The incident came after last week's high-profile feud between MGK and Slipknot's Corey Taylor, which began at another festival — Riot Fest — where both bands were playing that night. MGK's diss came during his own set and was directed at Slipknot when he said, "Hey, you wanna know what I’m really happy that I’m not doing? Being 50 years old wearing a fucking weird mask on a fucking stage."

Later, the two engaged in a back and forth on Twitter.

Machine Gun Kelly called Taylor "bitter" because his guest spot was rejected for the Tickets to My Downfall album, which prompted Taylor to share screenshots of emails between him and co-producer Travis Barker that showed that the Slipknot frontman had willingly bowed out of contributing to the record.

Picking a fight with one of metal's most beloved figures apparently did not sit well with a lot fans in attendance at Louder Than Life in Louisville, Kentucky. Throughout his set, MGK was met with torrents of boos from the crowd, while many raised their middle finger in his direction, as seen in the fan-shot footage directly below.

Machine Gun Kelly Booed at Louder Than Life Festival

One Twitter user, in response to the widely circulating news that fans "relentlessly" booed Machine Gun Kelly, shared a video of fans expressing support during the set. Feeling the headlines had been misrepresented MGK's time onstage, their ire was aimed at Loudwire in the tweet even though Loudwire had yet to report on the incident at that time.

Machine Gun Kelly retweeted this message and wrote, "I don't know why the media lies in their narrative against me all the time but all I saw was 20,000 amazing fans at the festival singing every word and 20 angry ones."

The multiple fan-shot videos, however, appeared to indicate there were far more than 20 disgruntled fans who were responsible for the resounding boos.

Throughout the set, MGK used much of his time onstage to engage in verbal altercations with members of the crowd, and, before the night was over, the musician threw a punch at a fan on the ground between the stage and the front row barricade which separated the festival crowd. That video clip can also be seen below.

Machine Gun Kelly Punches Fan at Louder Than Life Festival

The incident had a ripple effect in the rock and metal community and Trivium vocalist and guitarist Matt Heafy used it as an opportunity to take a swipe at Machine Gun Kelly, who was booed offstage in 2018 after dissing rap icon Eminem amid a longstanding feud between the two. Not long after, MGK abandoned his rap career in favor of the pop-punk style heard on last year's Tickets to My Downfall.

"I'd like to formally diss Machine Gun Kelly for 'being 31 years old wearing a fucking 16 year old pop punk cosplay identity on a fucking stage,'" tweeted Heafy, making a mockery of MGK's Riot Fest diss toward Slipknot.

In further jest, Heafy later said, "I'd like to publicly apologize for my tasteless comments about MGK. I just found out he's been afflicted by the Ligma [crude slang for licking genitals] variant. It's really getting real out there. Thoughts and prayers homie."

More footage of fans booing Machine Gun Kelly can be seen at the bottom of the page.

Machine Gun Kelly Booed at Louder Than Life Festival

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