New Hampshire's child protection agency is being sued over allegations that it allowed a couple to sexually assault their 4-year-old and 18-month-old daughters after the girls were placed in foster care.

The lawsuit was filed Wednesday by the girls' grandparents, who have adopted them. It alleges that the Division for Children, Youth and Families allowed the biological parents to have unsupervised visits with their children in 2013, even after police began investigating reports that the couple had molested other children at a homeless shelter where they were living.

Attorney Cyrus Rilee says the state needs to immediately increase staff at the agency and he hopes the lawsuit will lead to major reforms.

A spokesman for the agency did not immediately respond to a request for comment.