Chloe Campbell's devastated parents have spoken out, insisting that the little girl would never have wandered off by herself.
"I don't think there's any possible way she's wandered off. She wouldn't leave the yard by herself."
He told the Australian Associated Press that the family usually close the windows of their home at dusk each night to keep out mosquitoes, but he believes that one of the latches had not caught.
The distraught father tearfully added: "That's why we are blaming ourselves."
Apparently Chloe, along with sisters Janae, 8, and Britney, 5, were sleeping in the lounge the night she went missing, in a sisterly sleepover.
Mr Campbell explained: "When Janae woke to go to the toilet in the morning, Chloe wasn't in the lounge room.
"It's got to be someone who knows me... how they got in, where she sleeps. They knew she was sleeping in front of the TV."
He added: "I hope someone that's taken her is looking after her - giving her brekky, lunch, I don't know - I don't know what to think. Maybe someone took her who can't have kids or something like that.
"Just don't hurt her, she's tiny."
Chloe Campbell was reported missing just before 7am on Thursday from her home on Ridgeway Street, Childers - a town of roughly 1,500 people.
Police issued a 'child abduction alert' shortly after 9am and requested the message be broadcast on local radios every 15 minutes.
It says: "She is wearing yellow pants with love hearts on them and a white-coloured shirt with butterflies and bees pictured on the front. "Chloe could also be carrying a blue soft toy and a grey blanket."