Apparently someone put a gun in the oven, and it went off.
So this leads to
Rule 0. Eyes and Ears – Always wear eye protection, and hearing protection where warranted.
Rule 1. All guns are always loaded
Rule 2. Never point your gun at anything you are not willing to destroy.
Rule 3. Always keep your finger off the trigger until ready to shoot.
Rule 4. Know your target and what’s beyond it.
Rule 5. Never try to catch a dropped gun.
Rule 5-3/4. Don’t put your gun in the oven.