Update 7:00 p.m. MT - The incident was not related to the game, according to KCTV 5, but an attempted robbery gone wrong.
Police sources tell KCTV5 that a man and his son had gone to their vehicle during the game. When they arrived, they found another man rifling through the vehicle and a fight broke out. The man who apparently did not belong in the vehicle died.
Our original story is below.
Police arrested two people outside Arrowhead Stadium Sunday night for an apparent homicide, Kansas City police chief Darryl Forte wrote on Twitter.
Detectives investigating a homicide at Arrowhead Stadium. Two suspects in custody. Will update as info becomes available.— chiefforte (@ChiefForte) December 2, 2013
No information on the victim or suspects, or the fan affiliations of anyone involved, has been reported. It would be incredibly heartbreaking to learn that the outcome of the game - a game - could have resulted in such a terrible act and the loss of life. I know the overwhelming majority of both Broncos and Chiefs fans feel the same.
Seeing reports of homicide at Arrowhead stadium. Thought #Chiefs fans were extremely courteous to us when leaving. Saw very few incidents.— Peter Burns (@PeterBurnsRadio) December 2, 2013
We will have updates as more information becomes available.