Responding deputies tackled the suspect, Shae Holloway, as he was seen running from the home. The teen was reportedly covered in blood when he was taken into custody.
Arpaio said three other children, a 4-year-old, 9-year-old, and 17-year-old, were also found at the scene. The 9-year-old girl had been assaulted by the suspect and was transported to the hospital for treatment. She is expected to be OK.
Neighbors reported seeing the other children fleeing from the house, asking nearby residents for help.
Holloway was remanded as an adult and booked into the MCSO jail with a $1 million bond. He faces charges of second-degree murder, aggravated assault, and endangerment.