Twelve people, brothers and sisters between the ages of 2 and 29, were rescued by police officers who found them in a miserable condition - chained, in the dirt, on the verge of starvation - inside their home in a small town in California.
The parents have been arrested, remanded in custody and are expected to appear in court on charges of torture and endangering the lives of children, police said.
Authorities were alerted by a thirteenth victim: a 17-year-old girl who fled her home in the town of Peris for two hours in a car southeast of Los Angeles.
The young woman called the emergency number 911 with a mobile phone she found inside the house.
According to the office of the sheriff of Riverside County, police discovered the 12 people, who initially believed they were all young children, chained to beds in the house. "They were shocked to find that seven were actually adults."
"The victims looked malnourished and very dirty," the sheriff's office said in a statement.
The girl who notified the authorities - police said they initially thought she was about 10 years old - managed to escape and call 911 on Sunday.
The parents of the victims, David Allen Terpin, 57, and Louisa Anna Terpin, 49, were arrested and charged with torture and endangering the lives of children.
The financial guarantee that they will be paid for their temporary release has been set at $ 9 million, police said.
Six of the children are minors. The remaining seven were over 18. The police were told they were starving.
Police said in a statement that it was not clear why the parents were holding their children captive.
A neighbor who answered the phone on Monday noted that the neighborhood where the house is located is newly built. He said he did not know the Terpin family, and that he had not noticed anything unusual in the neighborhood.
The neighborhood consists of detached houses, usually of one level.
The parents are expected to appear before a judge on Thursday.