A five-year-old boy who was playing with a .22 calibre rifle he'd been given as a gift accidentally shot and killed his two-year-old sister in their Kentucky home, officials say.

The shooting happened on Tuesday in rural Cumberland county and the little girl was rushed to a hospital where she was pronounced dead, the state police said.

My first rifle: Crickett sells guns designed for children.

Cumberland County Coroner Gary White identified the girl as Caroline Starks and said the children's mother was cleaning the house at the time and had stepped outside onto the porch.

"She said no more than three minutes had went by and she actually heard the rifle go off. She ran back in and found the little girl," White told WKYT news.