Fire authorities say the cause of the Brin Building fire was determined to be electrical in nature.
Neenah-Menasha Fire Rescue says in a news release that the origin of the fire was located in the attic space between the second floor ceiling and the roof structure covering.
Fire authorities say the space is inaccessible. It also has a great deal of electrical wiring and conduit throughout the space that provides electricity to the apartments on the second floor.
Fire authorities say there were no other potential sources of ignition in the area and all other sources of ignition have been ruled out.
The property owner's insurance company provided an electrical engineer that helped evaluate the scene. The property owner is working with the insurance company to determine the future of the building.