Two possibilities leap to the front. The cupola was repainted and they were likely using those heat guns to strip paint.
Copper gutters were being installed which means there was soldering.
The work crew had just finished the project half an hour before the fire. :x
In Texas, they have some sort of grant or fund, something, that the counties can restore all their old courthouses. You know, they were built with the high ceilings and fire places. They got chopped up through the years with offices, lowered ceilings and stuff for central air. The one in Hill County was restored beautifully. They did the one in Cleburne, too, and even it isnt' so ugly anymore.
You should google Texas Courthouses. Look at the ones in Ellis and Hopkins Counties.