The deputies had been summoned by a 17-year-old daughter who jumped out a window and called 911.
Riverside County sheriff's Capt. Greg Fellows described the reaction of the mother, Louise Anna Turpin, 49, without elaborating. He said he did not know how the father, 57-year-old David Allen Turpin, reacted.
The situation at the home in Perris, about 70 miles southeast of Los Angeles, was discovered when the daughter escaped early Sunday, Fellows said.
The teen, who was so small that deputies initially thought she was 10 years old, showed them photographs that led them to believe her story so they went to the home to check on the family, Fellows said.
"The conditions were horrific," he said.
The children, ages 2 to 29, are all believed to be the Turpins' biological offspring, authorities said.
Fellows said the investigation has so far found no indication of sexual abuse but that the conditions amounted to torture.
"If you can imagine being a 10-year-old and being chained to a bed ... I would call that torture," he said.
The family had lived in Perris since 2014, and deputies had never been to the residence previously for any reason, Fellows said.
Social workers had never visited either, said Susan von Zabern, director of the county Department of Public Social Services.
The seven adult children were being cared for at Corona Regional Medical Center, said CEO Mark Uffer. He described them as small and clearly malnourished. They were being fed and were listed in stable condition.
"They're very friendly," he said. "They're very cooperative, and I believe they are hopeful that life will get better for them."
The parents were each held on $9 million bail and could face charges including torture and child endangerment.
It was not immediately known if they had attorneys. They were scheduled to appear in court later Thursday.
State Department of Education records show the family home has the same address as Sandcastle Day School, where David Turpin is listed as principal. In the 2016-17 school year, it had an enrollment of six with one student each in the fifth, sixth, eighth, ninth, 10th and 12th grades.
Neighbors in Perris, where modest but well maintained homes are tightly packed on suburban streets, said they were stunned by the arrests.
Andrew Santillan, who lives around the corner, heard about the case from a friend.
"I had no idea this was going on," he told the Press-Enterprise newspaper of Riverside. "I didn't know there were kids in the house."
Other neighbors described the family as intensely private.
A few years ago, Robert Perkins said, he and his mother saw a few family members constructing a nativity scene in the Turpins' front yard. Perkins said he complimented them on it.
"They didn't say a word," he said.
Social media photos show the family at Disneyland and Las Vegas. The most recent shots, from 2016, show the parents beaming after they apparently renewed their wedding vows and posed with an Elvis impersonator.
James Turpin, of Princeton, West Virginia, said Tuesday that he was surprised by the news reports about his son David. All 13 children are David's biological children. None are adopted, he said.
Turpin said he first heard about the matter Monday night in a call from a reporter. He declined to talk further.
"We're going to try to get to the bottom of it," he told The Associated Press.
He and his wife, Betty, told Wheeling, West Virginia, television station WTRF that David grew up in southern West Virginia.
The family moved to Southern California in 2011 from Johnson County, Texas, near Dallas, according to property records.
The Turpins filed for bankruptcy that same year, stating in court documents that they owed between $100,000 and $500,000. At that time, 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.