Officers were flagged down by a woman who spotted the boy near an empty lot around 11:40 p.m. The 3-year-old was dressed only in a diaper.
He was taken to University Hospital for an examination as a precaution.
Police said the boy had been with his mother prior to wandering off. The state Division of Child Protection and Permanency placed the child with relatives temporarily. Detectives from the department's Special Victims Unit are also investigating.
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