Article doesn't say exactly what the costume was but apparently wasn't a skunk costume, just black.
I'm not sure how big skunks grow down there but mistaking a 9-year-old for one is hard to believe. The only interpretation I see is he was basically shooting at a shadow without knowing or investigating what it was at all.
"Police will determine later Monday whether they will charge the shooter."
What? Did they mean "what they will charge him with"?