First responders found the child unconscious inside of an apartment at 395 Union Ave., in Irvington around 3:30 p.m. last Thursday, RLS Media reports.
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Neighbors told the outlet they watched helplessly as EMS performed CPR on the boy's lifeless body.
Law enforcement agents then took a man believed to be the boy's father into a vehicle belonging to the prosecutor's office around 9 p.m., after hours of investigating, authorities said.
Irvington Township Mayor Tony Vauss reportedly declined comment to RLS Media due to an open investigation, but expressed condolences.
A spokesperson for the prosecutor's office said only that an investigation was under way as of Monday morning.
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