Philadelphia (CNN) -- A 5-year-old girl abducted Monday from a West Philadelphia elementary school was found early Tuesday barely dressed and crying under a slide at a playground, police said.
A pedestrian walking by the park around 4:40 a.m. heard the child crying.
"When I got closer, it sounded clear: 'Help, help,'" the Good Samaritan, Nelson Myers, said at a news conference Tuesday.
"When I saw her under the slide I was shocked," he said. "She was there by herself and only had a shirt on."
"Five-year-olds don't escape. Someone put her at that playground," said Capt. John Darby, commanding officer of Special Victims.
The girl told Myers she "was stolen," Darby said.
The girl was taken by an unidentified woman wearing Muslim-style head garb with her face covered, authorities said.
The woman, walking with an umbrella, came to Bryant Elementary School shortly after school started Monday. She scribbled her name on a sign-in sheet, police said.
She did not show identification, but said she was the child's mother and wanted to take her out for breakfast, Darby said. She then proceeded to the child's classroom and asked for the girl by name.
"It appears this is not a random act," Darby said, adding that the woman "knew exactly what to do."
Darby said police do not know the abductor's identity, and that neither parent had given permission for the child to be taken out of school.
There were "no overt" signs of injury, but the girl was being examined for any assault, Darby said.
The investigation is ongoing, and police are continuing to search for the abductor or abductors.
After the girl disappeared Monday, Pennsylvania State Police sent out an Amber Alert and police announced a $10,000 reward.
Law enforcement and Mayor Michael Nutter turned to social networking sites Twitter and Facebook to ask for the public's help.
"It's disturbing that an adult is able to walk into a classroom and have the teacher release the child without knowing who the adult is," said Fernando Gallard, School District of Philadelphia spokesman.
Policy requires anyone signing out a student to go to the main office, and provide identification that matches a list of approved individuals, he said.
The substitute teacher who was in the classroom will not work for the city schools during the investigation, he said.
Officials are reaching out to all school personnel to make sure they understand the policy for signing out students.