SIOUX FALLS, S.D. -

Seven people are facing federal charges after law enforcement authorities on South Dakota's Pine Ridge Indian Reservation discovered two girls so severely malnourished that a pediatrician later compared them to prisoners of World War II concentration camps.

Court records show the discovery of the 2- and 3-year-old girls weighing 13 pounds each came on Nov. 11, when officers responded to a reported assault at a home on the reservation on the South Dakota-Nebraska border. The officers found the children lying on the floor, hidden under blankets, and only wearing diapers.

Authorities are accusing three of the seven of assaulting the girls. The five others are accused of not seeking medical intervention for or reporting the condition of the children to authorities.

The seven have entered not guilty pleas.