James Lewis, 38, was pronounced dead at the scene by York County Coroner Sabrina Gast.
According to a statement by Gast, Lewis was working at the home, located in the 4400 block of Marshall Road south of Rock Hill and owned by Dr. Robert Lesslie and wife Barbara, who were also killed, along with their grandchildren.
Lewis, a single father who moved to Gastonia 15 years ago, worked as an HVAC technician for GSM Services, a Gastonia firm owned by brothers Joel and Steven Long, which serves Gaston County and the greater Charlotte area.
GSM Services hired Lewis about eight years ago after Lewis vowed to go back to school and earn his HVAC certification, according to his parents, Tom Lewis and Linda Tucker. Lewis was an only child.