A California couple have been arrested after police found their 13 children allegedly held captive at home, some "shackled to their beds with chains and padlocks".
David Allen Turpin, 57, and Louise Anna Turpin, 49, were held on charges of torture and child endangerment.
The couple's children - aged two to 29 - lived in Perris, 59 miles (95km) south-east of Los Angeles.
Officers were alerted by one of the victims, a 17-year-old girl.
The teenager - who appeared to be "only 10 years old and slightly emaciated" - on Sunday managed to escape and call the emergency number using a mobile phone found inside the house, the Riverside Sheriff's Department said in a statement.
What did police find in the house?
Police officers later found "several children shackled to their beds with chains and padlocks in dark and foul-smelling surroundings".
The officers were "shocked" to discover that seven of them were actually adults aged between 18 and 29.
"The victims appeared to be malnourished and very dirty," the police said.
They are now being treated in local hospitals.
The head of one of the hospitals, Mark Uffer, told Reuters news agency: "It's actually heartbreaking for the staff and it's unbelievable what you see."
Mr and Mrs Turpin are now being held in jail with bail set at $9m (£6.5m) each.
How did they hide their secret?
James Cook, BBC News, Perris
On Muir Woods Road there is no hint of the horror inside number 160.
This is a smart suburban home with three cars and a people carrier gleaming in the driveway. The curtains are drawn but a decorative Christmas star can be seen hanging in one window.
The estate is neat and the houses on the road are spacious but they are close together. It is difficult to imagine how a family could hide such an enormous dark secret here.
And yet that is exactly what seems to have happened.
Neighbours are now engaged in soul-searching about whether they should have spotted that something was awry.
No-one seems to know how long the siblings may have been held captive and, of course, no-one can answer the hardest question of all - why?
What do we know about the family?
According to public records, the couple lived in Texas for many years before moving to California in 2010.
Mr Turpin has twice been declared bankrupt. At the time of his second bankruptcy he is said to have had a relatively well-paid job as an engineer at aeronautics and defence technology company Northrop Grumman.
However, with so many children and his wife not working, records suggest his expenses exceeded his income.
The children's grandparents said that they had not seen the family for four or five years.
James and Betty Turpin told ABC they were considered a good Christian family in their community and that "God called on them" to have so many children.
The family's Facebook page shows numerous photos and videos of them, apparently happy and smiling. Many posts contain comments from family or friends.
They appear to have renewed their wedding vows several times in recent years, often with their children present.
In a YouTube video, the couple are seen renewing their vows at the Elvis Chapel in Las Vegas.
Repeating after an Elvis impersonator, Mr Turpin tells his wife: "I offer you this ring as a symbol of my love, baby, baby."
The children laugh along with the impersonator, and clap as the couple kisses.
What about the children's education?
The grandparents said their grandchildren were home-schooled, but it is not entirely clear what that means.
On the California Department of Education website, Mr Turpin is listed as the principal of Sandcastle Day School - a private school operated out of his home.
The school was opened in March 2011, the website says. Six pupils were enrolled there, all in different grades.
In California, private schools operate outside the jurisdiction of the education department and most regulations. They are directly accountable to students and their parents or guardians, and the state has no authority to monitor or evaluate them.
Teachers at private schools in California also do not need to hold a valid state teaching qualification.
What do the neighbours say?
One neighbour told Reuters that the Turpin family "were the type that you didn't really get to know anything about them".
"Why don't we ever see the kids?" neighbour Kimberly Milligan asked.
"In hindsight, we would have never thought this, but there were red flags. You never don't hear or see nine kids."
She recalled on one occasion saying hello to the children as they erected a Christmas nativity scene.
But she said they stopped to stand frozen still, as if by doing so they would become invisible.
She described them looking at her "like a child who wants to make themselves invisible".
Recent cases of abduction, confinement and enslavement
- Argentinian Domingo Bulacio was jailed for 12 years in 2017 for repeatedly, over 20 years, raping his daughter, who says he kept her as a sex slave from the age of 11
- Cleveland abductor Ariel Castro held three women and a girl in captivity. He was found dead in September 2013 in his cell after being jailed for life the previous month for kidnap, rape and assault
- California couple Philip and Nancy Garrido kidnapped 11-year-old Jaycee Dugard and held her captive for 18 years. She was raped. They were jailed for life in 2011
- Krzysztof Bartoszuk held his daughter captive for six years, raping her and fathering two children with her. He was jailed for 10 years by a Polish court in 2010
- Austria's Josef Fritzl fathered seven children with his daughter who he kept locked in a cellar for 24 years. He was found guilty of charges including rape, incest, murder of one of the children and enslavement, and jailed for life in 2009.