Brokash - do you smell any gas? Go down into your basement and sniff. Go to any crawlspace and sniff. If you don't smell any gas, close up the windows and go to bed. Seriously.
There are two kinds of gas that's used in homes. On is natural gas: this is the stuff that's piped in to homes by a utility company. It is lighter than air and tends to dissipate quickly. (Chiefmickeymouse, is this what you have? I think it's pretty rare for a house on natural house to go boom from a leak, although it DOES happen, so always, always be careful!) Propane is the gas the is stored in a tank on your property. It's heavier than air and will collect in your basements or crawlspaces. This is the more dangerous form of gas.
Gas will be easy to smell here in the states as it will always have a rotten egg smell. If there is a STRONG Gas smell, GET THE EFF OUT. DO NOT STOP AND CALL THE FIRE DEPARTMENT. If you dial your phone inside, you may cause a spark that make the house explode! Do not unplug or plug in ANY electrical devices. Do not use a lighter. Don't do ANYTHING that may cause a spark. Just calmly, quietly, collect up all the people and animals in the house and get out!
If you just barely smell the rotten eggs, open your windows, don't do anything to cause a spark, shut off the source of the lead, wait until you don't smell the gas, then close the windows and be thankful you caught the leak before it became strong!