A man fatally shot a masked teenager in self-defence outside his neighbour's house during what appeared to be an attempted burglary and then discovered it was his son, Connecticut police said.
Troopers said 15-year-old Tyler Giuliano was killed by his father at around 1am in New Fairfield, a town of about 15,000 residents in the New York metropolitan area.
Authorities said a woman in the house believed someone was breaking in and called the teenager's father, Jeffrey Giuliano, who lives next door. The father grabbed a gun.
Troopers said Mr Giuliano confronted the teenager, who was wearing a ski mask and black clothing. They say the father fired his gun when the youth went at him with a weapon.
No charges have been filed against the father.