The Skagit Valley Herald reported police are treating the shooting as a homicide.
Police believe 25-year-old Trevor Braymiller is armed and dangerous. Braymiller is a convicted felon and is not allowed to have firearms.
Police first responded to calls of a child shot early Sunday.
Lt. Lin Tucker said Braymiller was a father figure to the child, although not his biological father.
The boy was taken to Skagit Valley Hospital but was pronounced dead there.
Tucker said the house where shooting occurred is well known to authorities. In 2011, police conducted a drug raid there. They have also seized firearms from Braymiller before.
Information from: Skagit Valley Herald, http://www.skagitvalleyherald.com
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