Officials say a couple noticed the child running down Kimball Street near 11th Street around 6 p.m. Thursday. The couple said the child looked lost and distressed.
The couple tried to help the girl, but she told the adults not to call the police, then ran away.
The girl was wearing a red, white and blue dress, with socks but no shoes. She has shoulder-length, dark hair and appears very thin.
Anyone with information is asked to call the Special Victims Unit at 215-685-3252.