Deputies responded shortly after 5:15 p.m. for a possible assault at the home, which is near the unincorporated Barbecue community.
Deputies arrived and found Danny Richards and Sabrina Richards dead inside a home and Clara Richards with a gunshot wound who was rushed to a hospital, but later died.
The sheriff's office said a 15-year-old suspect had been taken into custody.
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2 dead, 1 injured after shooting at Harnett County home