According to court documents, Malik Vincent Murphy told investigators that he carried out the attack so he could be alone in the house. He allegedly bought a knife several months ago with the plan of killing his entire family and burying the bodies in the backyard.
Officers were called to the home early Tuesday and tried to save Murphy's 5-year-old sister and 7-year-brother but they later died at the hospital.
The father, Jefferson Murphy, told investigators he was sleeping in his bedroom with his wife when he heard screaming in the basement. He said the teen had previously talked about killing his family.