In a tragic story out of Connecticut, a fifth-grade teacher is grieving the loss of his son today after a horrible accident at his own hands.

The man, Jeffrey Giuliano, was called next door by his sister in the early hours of Thursday morning because she was afraid an intruder was trying to break into her home. Giuliano went outside to investigate, and said he found a man dressed in black with a black ski mask covering his face; the man was brandishing a knife and approached Giuliano in a “threatening manner“, so Giuliano fired his gun, hitting the man in the head at least once.

But an investigation of the body revealed it was his own 15-year old son, and police are now trying to figure out why Tyler Giuliano was dressed in such a manner and wielding a knife.

The tragedy has hit the town hard; neighbors say father and son were close. A letter was sent home on Thursday afternoon to the parents of students at Tyler’s school, saying nothing would be said to the students on behalf of the school until the investigation was complete and all the facts were given.

“Our district has experienced a tragedy that has affected us deeply. … This tragedy was not discussed with the students as the facts were not clear. Students and staff will react in different ways. We will try to maintain our typical routine and encourage you to do the same,” the letter read.