OK, that being what you say it is, but I think the city has a right to confiscate any structure/material that is deemed to be a hazard to the community. In that these folks were smoking and cooking (by fire) within these tents, and the Fire marshall advised them to vacate for safety reasons, then I think it is NOT unreasonable to come in and destroy those structures. Municipalities condemn and knock down homes all the time. Why would one think this is different?
A tent is a hazard?
I think the theft as destruction was criminal. There's nothing wrong with having a fire in the tent. The frie marshal should have just made a rule, or had the police enforce an existing rule, which would have been with a ticket. They should have been arrested if there was a problem.
"Municipalities condemn and knock down homes all the time."
After due process of law and compensation has been given. They don't do that by making up their own rules!