An investigation is underway into what started a house fire in Brooklyn Sunday night that killed an elderly woman.

Officials say it started in the kitchen of a two-story home located at 546 77th Street in Bay Ridge.

When firefighters got to the scene, they say the fire was heavy, but they were able to extinguish it in about half an hour.

Kathryn Johnson, 89, was found unresponsive inside the home. 

She was taken to Lutheran Medical Center where she was pronounced dead.

No other injuries were reported.