In emergencies, calling 911 or your gas company will be the fastest way to address concerns about a dangerous gas leak. Your gas company or the fire department will respond and turn off your gas at the meter after they turn off your service. You will then be advised to call a certified plumber. ​In non-emergencies, call your gas company with your concern. It may result in them dispatching a tech to your home, or they may advise you over the phone to contact a plumber. If they do come to your home, the technician will make some assessment of your concern. If they determine a considerable liability, they will turn off your service at the meter and advise you to call a plumber.