Look, I'm not interested in another PI55ing contest with you. To clarify my point, I placed the priorities in order.
1) protect the child. obviously it depends on the lot and adjacent lots, but i would park far enough away to move the vehicle out of any immediate danger from stray gunfire while i can still observe.
2) i said to call the police and gather info
3) IF, and that's a big IF, i felt I could tackle the situation without endangerign my child, i would do so.
I would at least give it some effort. A couple of clear aimed shots on the BG as he's exiting the store at least. Maybe even lucky enough to get a few clear shots at him through the window if the background allows.
It's extremely unlikely that something bad will happen to my baby in a locked car in the time I'm gone, particularly because LEO will be there momentarily. Conversely, it's extremely likely that there is a BG waving a gun in my wife's face and she could get killed in the blink of an eye. I would want to be there to intervene if given the chance or to kill that SOB the moment I get a clear shot.
I live by the "commando" policy of "leave no (wo)man behind" particularly if she's my flipping wife!
Seriously, how could you sleep at night tearing off in your car, saving your own neck, leaving your wife behind.... "whew sally, that was a close one. looks like it's a bad night for mommy. let's go get some icecream...." and later when sally is older... "where's mommy?" "well sweetheart, we were at a store one day and a bad guy came into the store with a gun, so daddy took you and high-tailed it outta there."