All utilities mark their facilities in accordance with the American Public Works Association Uniform Color codes listed below:

Protect life and property-in that order. If leaking gas or high voltage is involved call 911. Gas explosions often result from breaks in the gas line near a building, filling the basement with gas. The break is often not at the place where the line was hit. Evacuation of the building and the surrounding area is critical.
Call the local utility damaged to report the damage and arrange for repair. Document the details of the hit, including your one-call ticket number, where the marks are, where you hit the line, the safeguards you took, and any other evidence you'll need to support your claim that you did all that was required of you as the contractor.
Remember to call Dig Line 2-Business days before you dig to avoid cutting underground utility lines.