Updated

Natural gas can be deadly if ignited by a flame or spark or if mixed with certain concentrations of air. Signs of a gas leak include a strong odor similar to rotten eggs and a roaring or hissing sound. The sight of bubbles in standing water, blowing dust or plants that appears to be dead for no reason are also signs of a possible leak.

If you suspect you have a gas leak, you should:

-- Leave your home immediately and take others with you

-- Open windows before you leave your house if the odor is faint

-- Call your gas company to report a suspected leak once you have evacuated the building

If you suspect you have a gas leak, you should not:

-- light a match or use lighters

-- activate light switches, electrical appliances, flashlights, doorbells, garage door openers, or telephones (including cellular), as they could create a spark.

-- start a car

-- re-enter your building until gas company inspectors have declared it safe

Sources: 

conEdison

New Jersey Natural Gas

Xcel Energy