The alleged attack happened Thursday and the girl's mother reported it to authorities Sunday, Acworth police Captain Wayne Dennard said.
"The victim said they were playing outdoors and the girl was forced into a wooded area where she was sexually assaulted, where one of the boys raped her," Capt. Dennard told The Associated Press.
The three boys — an 8-year-old and two 9-year-olds — were charged with rape, kidnapping, false imprisonment and sexual assault, Capt. Dennard said. They were due in juvenile court Monday afternoon. Their names were being withheld because of their age.
Capt. Dennard would not comment further.
Acworth Police Chief Mike Wilkie said said one of the boys was accused of threatening to hit the girl with a rock before the alleged assault. Chief Wilkie also said the investigation is "far from over," and investigators are looking into claims that after the alleged attack, the girl talked about it with her friends at a slumber party.
The father of the 8-year-old boy said his son had been falsely accused and had not had sex with the girl.
The sexual activity was consensual, and the girl accused her playmates only after her parents had learned she had sex, said the father, Brandon LeBlanc.
"There was no violence involved," Mr. LeBlanc said. "This is a clear case of a girl who didn't want to get in trouble with her parents."
He added, "In order to save her hide, she tried to blame it on rape."
The girl's mother, however, told WGCL-TV in Atlanta, "They do need to be taught a lesson because if they do it to her, they could do it to somebody else. And who knows when they become teenagers what they can do to other girls."
The case involves children from a working class apartment complex on the northern outskirts of metro Atlanta.
Mr. LeBlanc said the kids all played together, biking or throwing a ball around in the apartment complex's parking lot. He said his son is a third grader at a Baptist school who loves the Atlanta Falcons and is a batboy for his church's softball league.
Prosecutors had not received the case report from police on Monday, nor had they decided whether to try the suspects as adults.
"That decision hasn't been made," said Kathy Watkins, a spokeswoman for the Cobb County District Attorney's office. She had no further comment.
Acworth, 50 kilometres northwest of Atlanta along the shores of Lake Allatoona, is a town of about 17,000. Acworth police said their department has never before investigated allegations of rape where all the parties were this young.
"This wouldn't be normal anywhere, but especially not Acworth," Capt. Dennard said.