This is a very sad story, and my hear and prayers go out to the family.

I cant know for certain what happened, but indications are that he had improperly carried it in his waistband (ie without a holster).  As I have preached in the past, and will preach again, there is NO substitute for a proper holster.  This is not the first time that we've seen CHLs injuring or killing themselves when they improperly carry.  

Simply tucking a gun into your waistband or pocket is a recipe for disaster.  Personally, I recommend only a sturdy Kydex reinforced holster.  Not a flimsy fabric or even leather holster.  I don't fee safe unless the trigger guard is fully enclosed and covered by a non-collapsing non-flexible holster surface.

And while I'm on the subject, I recommend never NEVER putting your finger in the trigger well unless it is time to shoot.  I've see far too many people handle their weapon this way.  Even if you have a safety, even if the weapon is unloaded, your index finger should be straight out - pointing where the barrel is pointing, until you intend to shoot it.

Father accidentally kills himself in front of children at grocery store

A father accidentally shot and killed himself at the grocery store Sunday evening, according to the Spotsylvania County Sheriff's Office.
 
The father, a 45-year-old Spotsylvania man, was in his minivan with his children waiting for his wife to return a DVD to the Redbox outside the Giant Food Store in Harrison Crossing when he was shot, said Captain Elizabeth Scott with the Spotsylvania County Sheriff's Office.

The wife said she heard a pop and when she ran back to the minivan, her husband told her he thought he'd shot himself, said Capt. Scott. [UPDATE: Police say shooting victim had gun tucked in waistband]


http://www.kfor.com/news/wtvr-father-kills-self-grocery-store-20111114,0,3201030.story