A Connecticut man shoots and kills his teenage son after mistaking him for a burglar. WVIT's Doug Greene reports.

NEW FAIRFIELD, Conn. -- A popular fifth-grade teacher fatally shot a masked, knife-wielding prowler outside his house during what appeared to be a late-night burglary attempt, only to discover he had killed his 15-year-old son, police say.

Police said 15-year-old Tyler Giuliano was shot at about 1 a.m. Thursday in New Fairfield, a town just north of Danbury.

The teacher's sister was alone in her house next door to his when she believed someone was breaking in. She called her brother, and he grabbed a gun and went outside to investigate, police said.

The father confronted someone wearing a black ski mask and black clothing and fired his gun when the person went at him with a shiny weapon in his hand, police said.

Father sitting on grass

When police officers arrived, the teen was lying in the driveway of the woman's home with gunshot wounds and the father was sitting on the grass. The teen was pronounced dead at the scene, police said.

"All in all it's a tragedy," state police spokesman Lt. J. Paul Vance said.

The Associated Press said the teen's father, Jeffrey Giuliano, a fifth-grade teacher in town, had not returned a message seeking comment on what happened.

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NBCConnecticut.com spoke to members of the community about what happened.

"The fact that it was a father and son involved in the shooting and the way that it all happened, I think people quite frankly are devastated. This is a teacher who is very loved," one man told the station.

One of Giuliano's students described him as "one of the best teachers I ever had."

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The teenager, Giuliano's adopted son, was a student at New Fairfield High School, a short walk from the neighborhood where he was killed.

Superintendent of Schools Alicia Roy sent parents an email about what happened, The News-Times of Danbury reported.

"Our district has experienced a tragedy that has affected us deeply," she wrote, adding that students weren't told of the killing because all the facts weren't clear.

No charges have been filed. State police are investigating. An autopsy on the boy is planned.

The Associated Press contributed to this report.

Carol Kaliff / AP A blue tent protects the scene of a fatal shooting in New Fairfield, Conn., on Thursday.

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