"Not only is there a cost in terms of the volunteers' time, much of it given when they would otherwise be at work, but town water doesn't come cheap either, and a lot of water went onto this fire.
"Then there is the potential loss of jobs. The owner of this mill had been talking about getting it working again, and using it to train people in the milling industry, but I imagine that chance has gone now. All in all this hasn't been a good day for Kaitaia."
A pattern was beginning to emerge, however, and Mr Kerrisk had no doubt that someone would know who was responsible.
"Someone will have the information we need to get to this person and see that they get the help they need," he said.
"If anyone knows anything about who is responsible, now is the time to get hold of (Detective Sergeant) Trevor Beatson (phone (09) 408-6500), or Crimestoppers (0800 555-2111).
"The worry now is that if this person continues, other properties will be in danger. The mill has effectively been destroyed now, and there is a chance that the arsonist will go somewhere else."
Fire Service arson experts and business analysts were examining all recent fires in the greater Kaitaia area, collating data such as the day of the week and hour of the day that they were lit, to see if any connections could be made, and passed on to the police.
"All sorts of cross-matches can be made, but at the end of the day the person responsible won't be keeping it to himself, and it would be helpful if those people who know something came forward," he added.
Meanwhile Mr Kitchen noted once again that arsons tied up resources that could be needed elsewhere.
The Kaitaia Fire Brigade had received a call later on Thursday morning, which turned out to be minor, but arsonists needed to know their actions could put property and lives in danger.
Thursday's blaze had not been an easy one to fight - the last firefighters did not leave the scene until 1pm, and the site was kept under surveillance for hours after that - but the crews had done a very good job under difficult circumstances.
"These guys might be volunteers by name but they're professionals by nature, but you can say we're not happy," he added.
"Frankly I'm worried about my people in situations like this, and the sooner these fires stop the better."
The Kaitaia Fire Brigade was called back to the mill to extinguish smouldering rubble on Friday and again on Saturday morning. A spokesman said the problem was the large beams were holding considerable heat and would continue bursting into flames until what was left of the building was pulled apart so firefighters could deal with them once and for all.