Get out of the house right away, and don’t flip a light switch or touch anything electrical on the way, since even a small spark is a real risk in a gas-saturated space. Call once you’re a safe distance away and outdoors, not from a phone near where the smell is strongest. Don’t try to trace the source yourself or start opening and closing valves unless you already know exactly where the main shutoff sits and can reach it without walking back through the area.
That rotten-egg smell isn’t the gas itself; it’s mercaptan, a compound added deliberately because natural gas has no odor of its own and would otherwise be undetectable until something ignited it. For anything short of a suspected leak, new appliance connections and line work are permitted through Broward County, and a pressure test on every joint before the line goes into service is standard on any gas job we do, not an upsell.