Shocking moment NFL security guard is viciously attacked as wild brawl breaks out at Broncos-Chiefs game

Shocking footage from their game against the Kansas City Chiefs on Sunday shows a Denver Broncos fan viciously attacking an NFL guard.

A video circulating on social media initially shows two male spectators fighting at Arrowhead Stadium in Kansas City as a chaotic brawl breaks out in the stands.

But as a stadium employee tries to arrest one of the men involved, who appears to be wearing a Broncos jersey, another Denver supporter flies in and throws two punches at the staff member, the second of which knocks him to the ground.

Several members of the crowd then try to break up the situation when the violent fan grabs the staffer and falls to the ground with him.

DailyMail.com has contacted the Denver Broncos, Kansas City Chiefs and the NFL for comment.

More to follow.