Installation - SLRPNK

This happens when the metrical goes out in a house. Usually the waterlines will handle it, but if the house has pex the ground will go through the gas lines.

Especially if a high voltage line comes down on a gas meter for whatever reason.

Definitely run away and call professional… everyone i guess.

This would have also been prevented if the electrical install included an RCD. It would have tripped instantly when the neutral gets disconnected
Better yet to just have a bond to the gas and water pipes. In this instance, any current introduced to the plumbing has a direct connection to ground, which will allow current to flow freely and trip the breaker.