Rotten egg smell, hissing sound are key signs of a natural gas leak

DENVER -- Someone strikes an underground utility line every six minutes in the U.S. All it takes is one spark to cause a disaster.

Keeping families safe means knowing the signs of a possible gas leak and heeding those yellow flags that mark underground gas lines.

Whitney Nichols of Colorado 811 said a simple phone call before digging can mean the difference between life and death.

"You don't know where utility lines are. They can be a lot more shallow than you think and because of erosion they can actually shift," she said.

Make sure your family knows the signs of a gas leak, which include the smell of rotten eggs accompanied by a hissing sound.

Safety experts say you should leave the area at once then call 911 and your utility company. Call 811 before digging.