ALLOUEZ, WI (WTAQ) - State investigators say the cause of the massive apartment building fire is "undetermined".
Last month, the blaze caused about $3 million in damage to the Hilltop Place Apartments. It displaced about 100 residents.
The state fire marshal's office was called in to help investigate.
However, officials say there was so much damage, they can't give a concrete explanation of what sparked the fire.