The child was in the care of Delvin A. Montes-Funez, 33, who allegedly left him alone in an upstairs bedroom at 116 Main St. in Hackettstown before the building caught fire just before 1 p.m. on June 1, authorities said.
The boy was rescued by a Hackettstown Police officer who found him on the bed and carried him safely outside, authorities said.
Montes-Funez, of Hackettstown, was arrested Monday and charged with second-degree endangering the welfare of a child, police said.
He was being held at the Warren County Correctional Facility and is scheduled to appear in court.
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