The blaze broke out at about 9:00 a.m. at a home in unit block of Perry Street in Lambertville.
It took firefighters more than an hour to bring the blaze under control.
Flames eventually consumed the entire home and the property was lost.
One resident suffered smoke inhalation and was flown to a nearby hospital for treatment.
A firefighter suffered second degree burns on his ears and hands and was also taken to an area hospital for treatment.
No word on either of their conditions.
The house was converted into apartments and investigators say the fire started in the second floor.
The cause has yet to be determined.