Surviving so far on temporary phone line
This morning the gas guys were back at work. Apparently they did try to call in the break but they thought it was a cable-TV line and so weren't getting much luck with the cable company. Turns out if we'd had the wherewithal to notice that the plate covering the hole where they were digging in the lawn was in fact a wooden panel rather than a steel plate like they were using out in the road, we'd have been able to lift it out of the way on Saturday and the phone tech could have fixed it then, because the break was right there. Oh well. Anyway, the ball's in their court now.
As of this afternoon there's now a second hole in the lawn a few feet away. Meaning they found the water main and managed not to break it (thus far).