How do I handle a furnace explosion?

Evacuate the house immediately. Call 911 from outside. Do not re-enter the building for any reason, as there may be additional gas leaks or structural damage. If you can safely reach the gas shutoff valve outside, turn off the gas supply to the house, but do not delay evacuation to do so. After emergency services clear the scene, have your HVAC system inspected by a professional before turning any equipment back on. File an insurance claim if the home was damaged.