Responding firefighters were met with heavy flames in the rear of the building, which is detached from the main part of the house.
An unidentified female resident was pronounced dead at the scene.
A man who also lived there was found critically burned in the street.
He sustained burns over 30 percent of his body and was rushed to the burn unit at St. Barnabas Medical Center in critical condition.
Between eight and 10 residents of the multifamily home were evacuated by the flames.
The owner of the building was not at home at the time of the fire.
Firefighters put out the blaze in about 10 minutes.
The cause is under investigation by arson investigators.