Phoenix police responding to a report of hysterical screams say they found an 8-year-old girl partially clothed in a shed and four young boys running away.
The four boys, aged 9 to 14, allegedly lured the child with chewing gum, then "brutally sexually assaulted her" for 10 to 15 minutes, said Sgt. Andy Hill.
Prosecutors filed sexual assault charges against the boys on Thursday, officials said.
Hill called it one of the worst cases the department has investigated.
The boys are accused of holding the girl down while they took turns molesting her.
Police said the girl's parents criticized her after the violence, blaming her for bringing shame on the family. All five children are refugees from the West African nation of Liberia.
The 14-year-old boy was charged Wednesday as an adult with two counts of sexual assault and kidnapping, the Maricopa County Attorney's Office said. He is being held without bond.
The other boys — ages 9, 10, and 13 — were charged as juveniles with sexual assault. The 10- and 13-year-old boys also were charged with kidnapping, the office said Thursday.
Authorities said the victim was in the care of Child Protective Services after her parents blamed her for the rapes and bringing shame to the family.
"The father told the case worker and an officer in her presence that he didn't want her back. He said 'Take her, I don't want her,"' Hill said.
Hill cited the family's background as the reason the family shunned the girl.
In many parts of Africa, women often are blamed for being raped for "enticing" men or simply being in the wrong place at the wrong time. Girls who are raped often are shunned by their families.
In recent years, Liberia has made efforts to combat rape under the leadership of President Ellen Johnson Sirleaf, who has sought to dispel the stigma associated with sexual assault by publicly acknowledging that she was herself the victim of attempted rape during the country's civil war.
Phoenix investigators said the boys lured the girl to an empty shed July 16 under the pretense of offering her chewing gum.
Officers responding to an emergency call reporting hysterical screams found the girl partially clothed and the boys running from the scene.
The boys were being held in a juvenile corrections facility.
"This is a deeply disturbing case that has gripped our community," Maricopa County Attorney Andrew Thomas said in a news release Thursday. "Our office will seek justice for the young victim in this heartrending situation."
The girl's healing process will be particularly difficult, said Paul Penzone of Childhelp, which aids young victims of crime.
"These four boys used what was a ploy to entice her to a place where they could take advantage of her almost like a pack of wolves," he said.
"And what's so disturbing beyond the initial crime is the fact that a child needs to have somewhere to feel safe, and you would think that would be in a home with her own family," not in state custody, Penzone said.
The Associated Press contributed to this report.