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.
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".
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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 $9m bail and are due to appear in court on Thursday.