Hayes, 66, died from the attack in her yard in Dillon, a small city about 100 miles northeast of Columbia, said Capt. Cliff Arnette, spokesman for the Dillon County Sheriff's Department. It was not clear what might have provoked the pair of Rottweilers.
They belonged to a neighbor, who came over to help as Hayes lay bleeding, Arnette said. They turned on him too, biting him and causing injuries so severe he was still hospitalized Friday afternoon.
Arnette did not release the owner's name but did say that he has not been charged in the incident.
The dogs would not let emergency responders near Hayes or their owner. Deputies finally shot both of the animals, which were carted off by animal control.
Animal control officials removed two other adult dogs and one puppy from the owner's home late Thursday. County officials must decide if they will be put up for adoption or euthanized.
Authorities said they had received no formal complaints about the animals, but a woman who lives nearby says she believes the pair killed her dog earlier this week.
Georgia Thomas, who runs a florist shop in Dillon, said she was in the middle of the Valentine's Day rush Monday when her husband called to say their German shepherd puppy had been found dead.
Thomas said she then alerted neighbors and an animal control officer who lives in the neighborhood, but opted not to file a complaint.
Dogs have killed at least three other people in South Carolina in the past two years. In January 2009, the body of a 10-year-old boy was found in a man's yard after he was attacked by six dogs while walking home. The dog's owner is now serving a 5-year prison sentence for involuntary manslaughter.
In January, a 9-year-old McCormick girl was killed by a Japanese Akita three days after her grandfather bought the animal as a gift for his grandchildren. And in November, a 25-year-old man was killed in his Latta home when the family pit bull attacked him.
Also Thursday, a 3-year-old girl walking with her baby sitter in the coastal city of Port Royal was bitten in the head by a pit bull. Authorities said they planned to charge the owner of the dog, which animal control officials said they had picked up in the past six weeks after complaints of the animal running and jumping on neighbors. Across the state in Aiken County, a deputy shot and killed a pit bull that was circling and snapping at a jogger.
Authorities have not said what may have provoked the dogs that killed Hayes, but one animal control officials says it simply may have been the time of year. Female dogs typically go into heat in the spring, according to Jamie Nelson, director of Spartanburg County Environmental Enforcement, causing male dogs to become more aggressive as they look to mate.
"We deal with animals similar to dealing with a teenager," Nelson said.
Hayes' only child died in 1987, so she poured her love on her nieces and nephews, who all lived on the same land just outside of Dillon. She loved going fishing and working with her sister to grow seasonal vegetables in the garden, Odom said.
"It's one of those things that's meant to be," Odom said Friday. "She is in a better place."