It happened Tuesday on Lantern Road in Hicksville just before 12:30 p.m.
The other victims include the child's 47-year-old mother and the homeowner -- a 74-year-old woman who is a family friend of the mother.
The girl was bitten in the face and she has a puncture wound to the lip. Police say she was airlifted to Cohen Children's Medical Center and she is stable.
The mother and her friend were bitten on the legs. They are stable with non-life-threatening injuries.
Police say the dog attacked when the mother and daughter got home and went through the backyard gate.
The mother has lived in the house with her daughter for about two years.
Two dogs were taken from the home by officials with the Town of Oyster Bay.
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