The stunning rescue of Cleo Smith is being hailed as a miracle after the four-year-old was found alive and well in a locked house.
Her discovery came more than two weeks after she disappeared from her family's tent at a remote West Australian campsite.
WA police officers discovered Cleo about 1am on Wednesday, alone in a bed in the house in Carnarvon, some 75 kilometres south from where she went missing and just minutes from her family home.
The dramatic rescue was captured by an officer's body-worn camera.
"My name is Cleo," the little girl said when asked for her name.
A 36-year-old Carnarvon man is in custody and has been questioned over the suspected abduction. He is expected to face charges.
Police say he has no connection to Cleo's family and was not at the house when Cleo was found. The man was not on a list of known sex offenders in Carnarvon, a tourist gateway on WA's northwest coast known for its banana plantations.
There are no other suspects linked to the case.
Cleo was examined in hospital and found to be in good physical health. Police shared a photograph of her smiling and waving from her hospital bed after reuniting with her mother Ellie Smith and Ms Smith's partner, Jake Gliddon.
"Our family is whole again," Ms Smith posted on Instagram.
Police Commissioner Chris Dawson thanked the WA community, volunteers and officers involved in the 18-day search for Cleo.
"It's a wonderful day for this little girl and her loving family. I know the nation is rejoicing," he told reporters in Carnarvon.
One of the four officers who rescued Cleo, homicide detective Cameron Blaine, said it was "without a doubt" the best moment of his career.
"To see her sitting there in the way that she was, it was just incredible," Senior Sergeant Blaine said, describing the family's reaction to the news as ecstatic.
"Having seen her a couple of times this morning, she's a little Energizer bunny. She's a very, very sweet, energetic girl, very trusting and very open with us."
Authorities have been tight-lipped on the exact intelligence that led officers to Cleo's location.
The state government had offered a $1 million reward for information to find Cleo, but Deputy Commissioner Col Blanch said it was not expected to be claimed.
He said police received intelligence on Tuesday guiding them to the house, but the breakthrough was the result of investigators piecing evidence together.
Mr Blanch described seeing seasoned detectives "openly crying with relief".
"We were literally looking for a needle in a haystack and we found it," he told Perth radio 6PR.
"When she said 'my name is Cleo', I don't think there was a dry eye in the house."
Talkback radio lines were flooded by emotional callers as the news came to light.
NSW Police Commissioner Mick Fuller said it was an amazing story, revealing his WA counterpart had broken down upon learning Cleo had been discovered.
Premier Mark McGowan hailed the efforts of investigators.
"It often is a tragic outcome but this is great news and uplifting for the entire country," he said.
Cleo vanished from a tent at the Blowholes campsite, about 950km north of Perth, after the family arrived on October 16.
She was last seen by her mother about 1.30am that night.
The search for Cleo captured national attention, with her rescue described by University of Newcastle criminologist Xanthe Mallet as a "once in a lifetime miracle".
WA investigators spoke to more than 110 people who were at the campsite when Cleo went missing.
They sifted through more than 1000 calls to Crime Stoppers and trawled through vast amounts of material for forensic clues.
They had also been searching for the driver of a car seen leaving the campsite in the middle of the night on October 16.
Police had suspected Cleo was abducted by an "opportunistic" offender.
Prime Minister Scott Morrison welcomed Cleo's discovery, saying it was "wonderful, relieving news".