Police were called to the home near Snellville, Ga., Sunday night for a domestic incident, WSB-TV, Atlanta, reported.
Upon arrival, authorities found two people shot outside the home. Both victims were taken to Gwinnett Medical Center, where one died, The Atlanta Journal-Constitution reported.
The condition of the other victim was not reported.
Police called a SWAT team to enter the home where they found two more gunshot victims, both of whom were dead, WSB said.
Police said the gunman was not among the shooting victims.
Police haven't revealed a motive for the shootings or a description of the suspect, the Journal-Constitution reported.
The identities of the victims were withheld until their families could be notified.