A 17-year-old girl who alerted police to her siblings' captivity escaped through a window and called 911 from a deactivated mobile phone.
Riverside County Sheriff's Office police chief Gregory Fellows said it was important to "acknowledge the courage" of the teenager, who alerted officials to "get the help they so needed".
"The conditions were horrific," he said.
The girl was one of 13 siblings, aged between two and 29, who had been starved and held captive at a house in California.
Speaking at a news conference, police confirmed they are the biological children of David Allen Turpin (57) and Louise Anna Turpin (49) who were arrested after the emaciated girl escaped on Sunday.
UPDATE: Booking Photos Torture/Child Endangerment Investigation in Perris pic.twitter.com/4IdK7vPB2n
— Riverside County Sheriff's Dept (@RSO) January 15, 2018
Mr Fellows said the mother seemed "perplexed" when policed arrived at her home.
There was no information that suggested any of the children had been sexually abused, he said, but added that the investigation is still in its "very early stages".
He said it was not clear how long the family had been held in such conditions but that it appeared to have been for a "prolonged period".
Three of the siblings were found chained to furniture, he said. Six of the children are minors, while the other seven are over 18.
Mark Uffer, chief executive of Corona Regional Medical Centre, said it was "hard" to think of the seven older siblings as adults because "they're small" and it is "very clear" they are malnourished.
He added that all the victims had been "through a traumatic ordeal" but they are "very friendly and very co-operative".
Dr Sophia Grant, medical director at the child abuse unit at Riverside University Health Centre, said: "The long-term needs of these kids are going to be the psychological and psychiatric needs."
Perris mayor Michael Vargas told the news conference he was "truly devastated at this act of cruelty".
The children were found at their parents' home in Perris, which is about 70 miles east of Los Angeles.
After the 17-year-old girl alerted police, a welfare check was carried out and the grim discovery was made.
Police said the children were found "shackled to their beds with chains and padlocks in dark and foul-smelling surroundings".
Their parents have been charged with nine counts of torture and 10 counts of child endangerment, the Riverside County Sheriff's Office said.
They are being held in a detention centre on US$9m (€7.3m) bail and are due to appear in court on Thursday.
David Turpin's parents, James and Betty Turpin of West Virginia, told ABC News they are "surprised and shocked" by the allegations against their son and daughter-in-law, saying they cannot understand "any of this".
Kimberley Milligan (50) who lives opposite the family, said she had only seen the baby in its mother's arms and three other children since she moved to the street two years ago.
She described them as small and pale.
"Why don't we ever see the kids?" she said.
"In hindsight, we would have never thought this, but there were red flags. You never don't hear or see nine kids."
She said she was admiring Christmas lights in the neighbourhood two years ago and encountered three of the Turpin children and complimented them on the manger with a baby Jesus outside their house.
The children froze as if doing so would make them invisible, she said.
She said: "20-year-olds never act like that. They didn't want to have a social conversation."
A Facebook account, which appears to belong to both the mother and father of the family, features a series of photographs of the 13 siblings.
In one photo the couple are pictured with their children in front of mountains.
The family members, who are all wearing matching numbered "Thing" t-shirts from the Dr Seuss book The Cat In The Hat, are seen smiling.