Jason Douglas DeWitt, 38, was found dead alongside his son Grayson DeWitt after neighbours were forced to evacuate in residential area in Bel Air, Baltimore, US.
Officers responding to reports of a suicidal man retreated after finding a handwritten note saying explosives would be detonated if they continued searching the home, CBS Baltimore reports.
Neighbours were left “heartbroken” and said Grayson played with other children in the area and had not been harmed by his father previously.
The Harford County Sheriff’s Office is continuing its investigation into the apparent murder-suicide after police were called to the scene at 5.45pm last Thursday.
Officers attempted for hours to make contact with someone inside the home before forcing entry into the home.
There they found a handwritten note indicating explosives could detonate if the search continued.
Neighbours were evacuated and officers returned 11.30pm to find the father and son dead inside a bedroom, both with gunshot wounds to the body.
Sheriff Jeffrey Gahler said: “The answers probably aren’t going to come — the ‘why’, because there’s no reason to take the life of a three-year-old child.”
Officials said DeWitt did not have a criminal record and there were no prior calls to the house.
A neighbour called Andy said: “I can’t say I’ve fully processed what’s going on here, right? I mean, how do you explain to a 5-year-old that her friend died?
He added he never had any reason to believe Jason had harmed Grayson before Thursday.
“I don’t know what has to flip in your mind that you go from your parental instincts of protection to the opposite.”
Jessica Byrne, another neighbor, said her children had played with Grayson several times and added: “I can’t imagine someone would want to do that do their kid. I mean, I have two kids. I don’t understand it.
“We want (the kids) to share their feelings because we’re really not sure how they’re processing it.”