Emergency services were called to a Dixon Avenue property in Hawera on Friday where a block of flats were engulfed in flames.
The dwelling houses four individual flats which were all occupied at the time the fire started.
Two of the four properties were completely burnt out and the remaining two had smoke and water damage.
One person was taken to hospital with unknown injuries.
At 2pm the fire inspector arrived and further investigation is now underway.
A fire spokesperson on site confirmed the rental agency was working with the tenants to arrange temporary accommodation.