Police were called to the area of Bolton Avenue and Giles Court in Riverside, near Chalen Park, just before 1 a.m. Sunday on a report of a girl knocking on doors.
The girl told officers that she was asleep at her home when she was carried out by an unknown male and then dumped out of a car sometime later.
Investigators determined that the girl and two siblings were asleep at their home near Pike Street and Herman Drive when the suspect entered through an unlocked window.
Police said the single parent of the children was not home at the time.
"Around 11 o'clock, my brother said he heard screaming outside, but he thought it was just someone trying to break into the cars," said Natalie Garcia, a neighbor from across the street. "He looked out but he didn't see anything."
Two hours later in a neighborhood about four miles away, Celia Diaz had just fallen asleep when she heard someone knocking at her door.
"I thought that it was somebody that was drunk or something," Diaz said. "I went and looked out the window and I saw it was a little girl. She had gone to the neighbor's house and that's when I called police."
The girl knocked on at least two other doors for help.
Diaz said the girl's tongue was swollen and she couldn't remember where she lived.
"She didn't have any shoes, just a t-shirt and shorts," Diaz said. "She was saying to let her inside, that she was really cold. She seemed like she was drugged."
The girl was transported to Parkview Community Hospital in Riverside and later transferred to Loma Linda University Medical Center for injuries associated with the incident. She was listed in serious condition.
It's unclear if she was sexually assaulted by her abductor.
Police said they do not have a description of the suspect or vehicle.
Anyone with information is urged to contact Riverside police at (951) 353-7124.