BRUCE, Miss. (AP) — Authorities are investigating the cause of a house fire that killed a 57-year-old northeast Mississippi woman.

Local media report that Bruce resident Sandy McCullar had initially escaped the early Wednesday fire at her home, but was burned when she went back inside to rescue a pet.

McCullar suffered third-degree burns and was taken by helicopter to a Memphis, Tennessee, hospital, where she died later Wednesday.

Calhoun County Sheriff Greg Pollan says his deputies and the state fire marshal are trying to determine the cause of the fire.