Darla Napora's husband, Greg Napora, returned home Thursday to find his 32-year-old wife lying on the floor, covered in blood. She was pronounced dead at the scene.
Her husband then forced the dog into the back yard, but it somehow opened the fence and came down the driveway.
Pacifica Police Department Capt. Dave Bertini said the dog approached officers and first responders at the scene. Police shot and killed the dog.
The 2-year-old pit bull was not neutered. An animal behaviorist said that may have played a role in the attack.
A necropsy was being performed on the dog, as officials try to determine what prompted the dog to attack the woman.
The Associated Press contributed to this report.