University Of Phoenix Stadium
Overall view of University of Phoenix Stadium during the game between the Arizona Cardinals and the San Francisco 49ers, Dec. 29, 2013. Reuters/Mark J. Rebilas-USA Today Sports

A massive brawl between San Francisco 49ers and Arizona Cardinals fans at University of Phoenix Stadium was captured on video Sunday. The footage should serve as a virtual public service announcement about the dangers of fighting at a sporting event.

The fight took place at some point during the Cardinals’ 23-14 victory over the 49ers. The cause of the brawl remains unclear, but it took just a few seconds for the situation to spiral out of control.

Amid tense arguments and some minor shoving, one 49ers fan appeared to throw a punch at a Cardinals fan. Before long, an entire section of fans was throwing wild haymakers.

But the 49ers-Cardinals fan fight turned particularly violent when it spilled onto a nearby staircase. At the :25 second mark, a trio of brawlers fell headlong down the concrete stairs. Stadium security guards rushed to the scene in a bid to break up the fight -- and were promptly overwhelmed by a sea of humanity.

By the end of the fracas, dozens of punches were thrown, a security guard was choked, the stadium stairs were covered in blood and more than one fan learned the hard way that novelty football helmets don't provide actual protection to the head. One dude even lost a shoe. All in all, it wasn't a good look for anyone involved.

Glendale police arrested one person in connection with the brawl, Arizona Sports 98.7 FM reports. Nearly everyone else involved in the fight was ejected.