“So all they need is electric.”
Call the electric company, and tell them you’re re-wiring the mains, and have them pull the meter. Try the same with the water. Depending on the meter, you might be able to turn the gas off yourself. Or report a gas leak! Don’t turn the water off yourself cuz you need a key wrench that only the water company is supposed to have. Doing it yourself might be a felony!
Couple of years ago we fried a main breaker at our house. Called an electrician who had to pull the meter before he could install a new one. I think that would work on squatters. ;)
Water meter can be turned off with a “water key” available at any hardware store.
Gas meter can be turned off with a crescent wrench.
Electrical meter can be pulled by removing the retaining ring and pulling the meter straight out. This may not shut it off if it is one of the “bypass meters” like you see on commercial businesses. The retainer ring is flimsy enough that I usually just break them for time purposes.