The suspect is identified as 35-year-old Humberto Guzman-Garcia, who has a last known address in the 300 block of Lake Road in Avondale.
According to District Attorney Tom Hogan, Guzman-Garcia knocked on the front door of the victim's Avondale home around 3:30 a.m. on Sunday, June 10.
The girl opened the door, and that's when Guzman-Garcia allegedly grabbed her and took her outside and behind a shed.
The child's parents noticed she was not in her bedroom and her father went outside to look for her, only to find his daughter being sexually assaulted behind that shed, Hogan said.
The child reportedly told investigators, "A monster took me."
RELATED: Mother gets life prison term, boyfriend sentenced to death in 8-year-old's torture-killing
Guzman-Garcia ran away but he was allegedly found hiding out in an abandoned car and was positively identified by the father.
The suspect is a complete stranger to the family, Hogan said. Investigators are trying to figure out if he observed the victim earlier in the day and followed her to the family's home.
"This crime is every parent's nightmare. A monster comes out of the night, abducts your child, and sexually assaults her. This is proof that evil exists in this world," Hogan said.
Guzman-Garcia has been charged with kidnapping, aggravated indecent assault, attempted rape, and related charges.
He was arrested, failed to post bail, and was remanded to Chester County Prison.
Due to the nature of the crime, investigators are worried there are more victims out there. Anyone with information is asked to contact Pennsylvania State Police Trooper Stefano Gallina at (610) 268-2022.