The 13-year-old girl and 14-year-old boy told authorities that the imprisonment was a form of discipline but no information has been released on why they were being punished. The Iowa Department of Human Services said it removed the teens from the home in Ankeny after one of them told a school employee about their confinement.
The 45-year-old father and 44-year-old mother, who were arrested Wednesday, were also charged with neglect or abandonment of a dependent person. They each posted $22,000 bond and were released after a few hours.
Police said the children reported being locked in the basement after school and on weekends for three to four weeks as a form of punishment. It was not clear why the teenagers did not speak up sooner.
DHS spokesman Roger Munns said the children are being cared for in a safe place but that state law prevents him from discussing any details of the case. Munns would not say if the agency had investigated any previous allegations against the parents.
Ankeny Police Chief Gary Mikulec and the Polk County Attorneys' office did not immediately respond to messages from The Associated Press Thursday morning.
A phone number listed for the parents is no longer in service, and online court records don't list an attorney for them. The parents also did not respond to Facebook messages from The Associated Press.
Neither one of the parents has much of a criminal history. The father was caught speeding in August, according to Iowa court records online.