No one was reported to be in the building at the time of the fire, the spokeswoman said.
A fire investigator will head to the scene today.
People have taken to social media in support of Campbell and the butcher shop.
One said: "Sad to see a long-standing business hurt like this (also Malcolm, his wife and staff). Butchers are heart of the community people, and a essential supplier in the community."
Another posted: "Sorry to hear. Someone who has given everything to Kawerau."
Police said if anyone had any information about this incident or the people involved please call 105 and quote the file number 211007/6437.