My family and I used to go to that area of Arvada fairly frequently as the AMC we liked to go to is close to there.

My wife (former Deputy Sheriff) and I were talking about this yesterday and both think the likely scenarios based upon the reporting were as follows:

• Shooter shot a police officer
• Shooter was likely not white since they are not mentioning race. If he was white they'd be saying it everywhere.
• The hero here stopped the shooter by shooting him
• Police arrive on the scene for an officer down situation see the hero and shoot him