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A Philadelphia 5-year-old who was taken from her elementary school by an unknown woman was found screaming for help in a park outside the city early Tuesday.

Upper Darby police Superintendent Michael Chitwood tells the Associated Press a man walking down the street early Tuesday heard cries for help and found Nailla Robinson hiding under a jungle gym in a nearby park.

He says she's been taken to the hospital to be checked out, but that she's OK.

MyFoxPhilly.com reports the mayor had announced a $10,000 reward for information leading to the safe return of Nailla, who was taken out of her classroom by a woman who told the teacher she had signed the girl out for the day.

An official told the Philadelphia Daily News that the woman introduced herself as "Tiffany," but her signature in the school visitor log was illegible.

Police discovered that the girl was missing later that afternoon, when a caretaker from the child's after-school program came to pick her up.

Nailla's mother appeared on local media, tearfully pleading for her safe return.

School district spokesman Francisco Gallard told the newspaper that allowing the girl to leave school with an unknown adult was a "serious break in procedure." Gallard said the woman didn't wait at the school's front office as is district policy but went to a classroom and told a teacher that the child had been "checked out" of school.

"That is completely against our protocol," Gallard said. "An adult is not allowed to go to any classrooms to check children out. They're supposed to go to the administrative office, their ID is supposed to be checked, and they are supposed to be checked to see if they are the guardian of record or parent. If they are, then they call (the) classroom for the child to be brought down, because we don't want adults roaming the building."

Walker said surveillance video of Nailla leaving school with the woman showed that the girl didn't appear to believe she was in any danger. Police said Nailla was often picked up by different people from the after-school program.

State police told MyFoxPhilly.com the woman who took the girl was wearing Muslim-style clothing and appeared to be pregnant.

The investigation into the case is ongoing.

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The Associated Press contributed to this report.