Train!

[Great-Kazoo]

As I said, I can shoot MOH (Minute of Hajji: not a perfect grouping but accurate enough for consistent hits on a man sized target) all day long at 100m with my carry gun. It takes effort, but its by no means impossible or even very difficult to do.
And again, its 65 yards from door to door. Distance to the gunman was probably less than that, and even door to door is by no means an incredible feat.
Sure, if you miss and by chance hit one of the people in there, you could be faced with charges. Simple solution: don't miss. Really, its that simple. Training will get you there.
Were I in that situation, I'd probably close distance. Closer = easier to get a grasp on the details of the situation and of course an easier shot at the target, not to mention the cover provided by obstacles in the parking lot.
Had the BBQ guy done so, and stopped the gunman while he had the chance, lives could have been saved.
As trlcavscout said, there are situations where its best to get the hell out of dodge or be a good witness. And "active shooter" scenario where large body counts are the goal is not one of those situations IMO.

I agree with training, in my CCW class i cannot stress training enough, 1 or 2 classes do not a proficient gun owner.
Since i already posted i will add this. Targets DO NOT SHOOT BACK
Unless you are training under fire (Simunitions) all the time, or have been involved in a shoot out, you will never know what it is like to have some one return fire.
Arm chair quarterbacking doesn't play in the real world.
Example: Columbine, had numerous LE depts on site, unfortunately the Com between depts was fuked. However with unknown assailants NOT ONE LE entered the building to stop the threat.
I am at the dry cleaners 2 doors down from the IHOP and i hear gunfire. I see #1 assailant with a rifle. All of a sudden Shooter #2 makes an appearance from a building same side of the street as me.
Do I engage Shooter 1 or 2, Is shooter 1, even with rifle going after shooter #2's accomplice or shooter 2 accomplice of 1??? Is shooter 2 an LE without ID as happened in NY recently and was shot by another LE?? Do i draw and engage, what happens if an off duty LE was on site and see's me running towards IHOP? More than likely he would order me to halt or shoot since he also does not want to draw fire.
I am also one who runs towards the train wreck as i have to live with myself and sleep at night. UNLESS i have a clear picture of what is going on engaging would be a call only made at that time. YMMV.