An off-duty New York City police officer saw the child alone around 10:20 a.m. Saturday in the parking lot of Carmans Plaza on Carmans Road in Massapequa.
Police said the child's 37-year-old father came back to the scene and couldn't remember where he had left the girl.
Authorities said he was observed in a delusional state, and had an accelerated heart rate.
He was admitted to the hospital, and is facing a charge of endangering the welfare of a child.
The girl was evaluated at the hospital and released to her mother.
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