The incident was reported in the 300 block of Ogden Avenue on Friday afternoon.
It is believed the child fell from the 3rd-floor window of the building, according to a witness.
The child's parents came rushing out of the building as soon as he fell and took him to a local hospital with serious injuries.
He was then transported to St Joseph's Children's Hospital in Paterson with pediatric trauma.
The investigation is ongoing.
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