I grew up around guns. My father was an avid outdoorsman, if it wasn't hunting season the only thing that kept us off the range some days was fishing.
I learned at a very young that there was no such thing as an unloaded gun, and you never ever pointed a gun at something unless you wanted to shoot it. To this day I can not touch a gun without checking the chamber, and even if I just checked it, the muzzle is always pointed at the ground.
The question here is: were these people attacking Mr. Baldwin? If yes then he can claim self-defense. If he was holding a gun that discharged and killed some one, he should be charged with negligent homicide. There may be some defense to that, I don't know what it would be.