I see you've never taken a gun safety class. There are rules you're supposed to follow to prevent exactly this kind of shit. Responsible gun owners are absolutely anal about following those rules. And they're really simple rules. Here's the version from gunpro.com:

1. Treat all guns as if they are always loaded.
2. Never let the muzzle point at anything that you are not willing to destroy.
3. Keep your finger off the trigger until your sights are on target and you have made the decision to shoot.
4. Be sure of your target and what is behind it.