Oh man I am sorry. Also glad you and the family are safe.
Is your water heater in your garage? That + gas leak is a common source of garage car fires.
Those of you who park your car in the garage, please consider a simple exhaust fan/vent at ground level with an electric fan, to remove gas fumes.
Shutter Exhaust Fans
An alternative is an attic gable fan, if you have (or can cut) a vent from your garage to the attic overhead. The advantage there is that it keeps the temperature in your garage down, and your attic, and therefore also your house. Thermostatically controlled ones are available.