Steve Berry with the Mesa Police Department said a fight broke out in the front yard of the home in the area of 72nd Street and Lakeview around 5:30 a.m.
The homeowner came out of the house to see his son being attacked and allegedly shot the person beating up his son.
Others involved reportedly took the victim to the hospital where he was pronounced dead.
Berry said the son knew the attacker.
It is unclear what led to the fight.
The investigation is ongoing.