Morris Township police responded to the home Sunday and found a neighbor administering CPR to an unconscious 4-year-old girl on the lawn.
Another neighbor was caring for the girls 6-year-old sister. Officials say she was conscious, but lethargic.
The younger girl was pronounced dead at Morristown Memorial Hospital. The 6-year-old was being treated for non-life-threatening injuries.
Officials have not released the girls' names or said how the one child died.
Information from: Daily Record, http://www.dailyrecord.com