DETROIT – A 71-year-old woman died Saturday after being attacked by a pit bull in her home, Detroit police said.

It happened around 8 p.m. in the woman's residence in the 2000 block of Ferdinand Street in southwest Detroit.

Police said the dog bit the woman, knocked her to the ground then mauled her.

The woman was found by her granddaughter in a room on the home's first level, police said. Family members identified her as Elizabeth Rivera.

There were four dogs at the home, police said. It's unclear if all of the dogs were involved or just one. The dogs were placed in a room upstairs until Animal Control personnel arrived to secure the scene.

The pit bulls were removed from the house one by one as Rivera's family looked on in disbelief.

VIDEO: Animal Control arrives at scene of pit bull attack in SW Detroit

Neighbors stepped outside in the southwest Detroit neighborhood to loud screams.

"My heart just goes out to them and their family," neighbor Saira Barrera said.

It's unclear what forced the dogs to turn on the grandmother.

"We have no idea and even family members are baffled," Capt. John Serda said. "I feel so bad for the family members to have dogs that belong to your family do something like this is beyond comprehension."