When you go to a football game, typically all of the action is on the field.

But during Sunday's San Francisco 49ers-Arizona Cardinals NFL game at University of Phoenix Stadium in Glendale, Ariz., there was a ton of action in the stands as well.

Check out the Live Leak video below of a pretty brutal brawl that broke out between some fans in the stands.

At one point, the brawl cascades down the steps, where the punches fly and the blood begins to flow. Stadium security finally managed to break it up and haul everyone away.

Oh, sports.

Source: Free Beer & Hot Wings