A Southern California couple is in custody on suspicion of torture and child endangerment after 12 of their children allegedly were found captive in the couple's home, with some of them shackled to beds.

David Turpin, 57, and Louise Turpin, 49, were each being held on $9 million bail, the Riverside County Sheriff's Office said in a statement Monday afternoon.

Authorities said the investigation began after a 17-year-old girl "escaped" from the home in Perris and called 911 early Sunday to report that her 12 brothers and sisters were being held by their parents.

The sheriff's office said investigators initially believed the "slightly emaciated" girl was just 10 years old when they first saw her.

David and Louise Turpin are pictured with their 13 children in April 2016. (Facebook)

When officers and deputies went to the Turpins' home, they found "several children shackled to their beds with chains and padlocks in dark and foul-smelling surroundings," according to the sheriff's office. The statement added that the parents were "were unable to immediately provide a logical reason why their children were restrained in that manner."

Authorities initially believed that all the victims they found were children. However, investigators eventually discovered that seven of the victims were over 18.

The Turpin home in Perris, Calif. (Google)

The sheriff's office said the victims "appeared to be malnourished and very dirty" and were given food and drinks after they "claimed to be starving." They were sent to two local hospitals for treatment. Their conditions were not immediately known.

The Los Angeles Times, citing public records, reported that the Turpin home's address was listed as the location of the Sandcastle Day School, a public K-12 institution that opened in 2011. David Turpin was listed as its principal. In the 2016-17 school year it had an enrollment of six with one student in each of the fifth, sixth, eighth, ninth, 10th and 12th grades.

The Turpins had lived at the home about 60 miles southeast of Los Angeles since 2010, the Times reported, and had previously lived in Texas.

The New York Times reported that the Turpins filed for bankruptcy in 2011, stating in court documents they owed between $100,000 and $500,000. At that time, David Turpin worked as an engineer at Northrop Grumman and earned $140,000 annually and his wife was a homemaker, records showed.

Their bankruptcy lawyer, Ivan Trahan, told the New York Times he never met the children but the couple "spoke about them highly."

"We remember them as a very nice couple," Trahan said, adding that Louise Turpin told him the family loved Disneyland and visited often.

Neighbor Kimberly Milligan told the paper that she rarely saw the Turpin children and said the few she did see were very pale.

"I thought the kids were home-schooled," Milligan told the Times. "You know something is off, but you don’t want to think bad of people."

Milligan also recounted that she once saw some pre-teen children putting up Christmas lights on the Turpin home. When she greeted them, Milligan said, "They looked at us like a child who wants to make themselves invisible."

Another neighbor, Robert Perkins, told the Associated Press he and his mother saw a few family members constructing a Nativity scene in the Turpins' front yard a few years ago. Perkins said he complimented them on it.

"They didn't say a word," he said.

The Associated Press contributed to this report.