Ruby-Lea Burke was mauled by up to four dogs.
Two of the dogs involved in the attack. (Nine News)
Three of four dogs that killed a three-year-old girl and injured her younger sister and baby sitter in southern NSW have died.
Ruby-Lea Bourke was mauled by four-mix breed dogs at the home of her baby-sitter in Beechworth Street, Whitton, near Leeton, on Wednesday.
She died at the scene while her 16-month-old sister Lilly, survived the attack with serious injuries to her face and body.
The girls had been in the care of a 45-year-old woman, a friend of their mother's and the owner of the dogs.
She was also injured in the attack and is in a stable condition at Griffith Base Hospital, where she is expected to stay for the next few days.
Police requested the four dogs be euthanased.
ABC television reported that the dogs had been sedated with tranquilisers and impounded on Wednesday night, but three of the four dogs were found dead at the Leeton pound on Thursday morning.
According to a local council ranger, they died from a combination of sedative drugs, heat stress and obesity, the ABC said.