Multiple members of "Bills Mafia" were seen brawling at Highmark Stadium on Monday night during the Bills’ loss to the Denver Broncos.

The altercation in the upper decks began when one fan, wearing a No. 17 Josh Allen Bills jersey, tossed his beer onto a group that took obvious exception to the matter.

But it got uglier once the fans in section 314 started throwing fists. 

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One of the fans who had the beer thrown at him went after the Allen jersey-wearing fan, which led another to join the fistfight. 

There was one man who tried to step in to stop the fight, but he was thrown down the stairs violently as the melee continued. 

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In the video, which was posted by X user @KyleEllisWV, there isn’t any view of stadium security or law enforcement coming down to break it up. There have also been no injuries reported. 

This was a night to forget in Buffalo, as Allen and the Bills’ offense committed four turnovers in a stunning 24-22 loss that came down to the final play of the game. 

Broncos kicker Wil Lutz had missed a 41-yard field goal that would’ve seen Buffalo steal the victory in the end, but the Bills were called for too many men on the field, allowing a redo of the field goal. 

Lutz stepped into a 36-yard try this time and drilled it down the center, as Russell Wilson and the Broncos came away with a big victory against a playoff contender. The Broncos moved to 4-5 on the year, while the Bills fell to 5-5. 

Allen threw two interceptions, one of which went right through the hands of wide receiver Gabe Davis and the other a poor throw that Fabian Moreau picked off just before the end of the first half. 

He also botched a handoff to running back James Cook, who fumbled on the first play of the game for the Bills, in the second half.