A Southern California couple are in custody after one of their daughters called 911 and led authorities to their home on Sunday. There, the Riverside County Sheriff's Department says it found 12 of the teen's siblings inside, including "several children shackled to their beds with chains and padlocks in dark and foul-smelling surroundings."

Of the 13 siblings living at the home in Perris, Calif., officials say six were under the age of 18. The siblings ranged in age from 2 years old to 29, and the daughter who sought help was 17 — though when law enforcement officers met with her, "she appeared to be only 10 years old and slightly emaciated."

"Deputies, when they arrived inside the house, noticed that the children were malnourished," Capt. Greg Fellows, commander of the Perris Sheriff's Station, said at a news conference Tuesday. "It was very dirty, and the conditions were horrific."

Law enforcement officers arrested their biological parents, David Allen Turpin, 57, and Louise Anna Turpin, 49. Each of the parents has been charged with nine counts of torture and 10 counts of child endangerment. Each is being held on $9 million bail.

"If you can imagine being 17 years old and appearing to be a 10-year-old, being chained to a bed, being malnourished and [having] injuries associated with that — I would call that torture," Fellows told reporters.

All 13 victims were hospitalized for examinations and treatment. Although the Riverside University Health System declined to describe the minors' condition, Corona Regional Medical Center CEO Mark Uffer said the seven adults are "stable and they're being fed."

"It's hard to think of them as adults when you first see them because they're small, and it's clear they're malnutritioned," Uffer said at Tuesday's news conference.

Fellows explained Tuesday that the parents, who have lived in Perris since approximately 2014, had been home-schooling their children. When confronted by the police Sunday — according to the statement released Monday — "the parents were unable to immediately provide a logical reason why their children were restrained in that manner."

"It seemed that the mother was perplexed as to why we were at that residence," Fellows said. He added that law enforcement "had no prior contacts at that residence regarding any allegations of child abuse or neglect."

David Turpin's parents, James and Betty Turpin of West Virginia, told ABC News that they were "surprised and shocked" at the allegations because their son and daughter-in-law were "a good Christian family." They said they had not seen the family since visiting California four or five years ago.

The Los Angeles Times, citing public records, reports that the couple had moved to California from Texas several years ago and that they had declared bankruptcy twice.

Ivan Trahan, a lawyer who had represented the couple in their most recent bankruptcy filing, in 2011, was quoted by the Times as saying that the Turpins seemed like "very nice people who spoke highly of their children" but who had fallen into financial problems.

Trahan said David Turpin had worked as an engineer for Northrop Grumman. A spokesman for the defense contractor confirmed to the Times that he was employed there until 2010.

However, Kimberly Milligan, 50, who lives across the street, was quoted by the newspaper as saying that when she first moved in she saw a woman outside the house with an infant, but eventually stopped seeing the child. Over the years, Milligan said, she would occasionally see three children who looked like preteens.

"I thought the kids were home-schooled," she said. "You know something is off, but you don't want to think bad of people."

Considering the proximity of the houses, Milligan questioned aloud: "How did no one see anything?"

Milligan was quoted by Reuters as saying that two years ago around Christmas she saw three of the older Turpin children outside and complimented them on a Nativity scene outside their house. She said they "froze [as] if by doing so they could become invisible."

"Twenty-year-olds never act like that," she told the news agency. "They didn't want to have a social conversation."

Still, authorities lauded the bravery displayed by the 17-year-old daughter in calling attention to the situation Sunday.

"I appreciate the courage that this juvenile had," Fellows said Tuesday, "to escape that house and get out there and report this to law enforcement."