The fire broke out around 8:30 a.m. on Tuesday at 60 Haines Street in Bloomfield.
When officers arrived at the scene, authorities say they discovered a woman in a wheel chair at the front door of the home. They managed to get her to the front lawn where they attempted unsuccessfully to revive her.
Esther Utkewicz, 65, was pronounced dead at the scene.
Her son, James Utkewicz, 44, was also discovered in the house. He was transported to Mountainside Hospital in Montclair where he remains in critical condition.
The Essex County Prosecutor's Office and Bloomfield police and fire officials are investigating the cause.