Updated

A dog described as very protective of its elderly owner mauled the 91-year-old woman to death and then was shot and killed after it charged at officers, authorities said.

Mary Stiles was found dead Monday afternoon in the kitchen of her brick bungalow.

After the attack, a neighbor shot at the 90-pound dog outside the home when it appeared ready to attack some children, according to witnesses. When police arrived, the animal — a mix between a pit bull and an American bulldog — charged them and was killed.

The dog, named Butch, had belonged to Stiles' grandson, and she adopted it after the grandson died a year ago, neighbors said.

No one knows why Butch turned against her, although animal control officials are testing the dog for rabies.

"Neighbors were saying that dog was very protective of the woman," police spokesman James Tate said. "For some reason, it snapped."