From my understanding...former GWVPD Officer was pissed about kids driving fast in his neighborhood, proceeds to get in car and follow said teens. Argument ensues...teen pulls gun, fires first and gets a non-lethal hit. Former officer open fires and kills teen.

Aurora teen dies after exchanging gunfire with former police officer (msn.com)

100% avoidable situation. There used to be a house down the street from me about a year and a half ago where the occupants would buy cars at the auction, give them a tune up and drive extremely fast down the street. Aurora PD talked to them, which helped for about 6 months, then it started up again. One day my neighbor told me there were a lot of police, fire & EMS activity at their house the night before. I apparently slept through it all. Never saw them again after that. Not sure what happened, but the problem corrected itself. I'd be curious to see where this case goes.