Trooper Stu Recke said a father and daughter who survived the blaze are in hospital in Nashville, Tennessee. He did not know their conditions.
A relative said a couple in their 30s lived in the house with their nine children.
Trooper Recke said the adult who fled the fire about 2am local time in the Depoy community of Muhlenberg County told first responders that most of the family were still inside the house.
Investigators were working to determine the cause of the blaze.
Trooper Recke said eight bodies were found in a master bedroom while the ninth was found between 10ft and 15ft away.
He identified the dead as 35-year-old LaRae "Nikki" Watson, and her children, Madison, 15, Kaitlyn, 14, Morgan, 13, Emily, nine, Samuel, eight, Raegan, six, and four-year-old twins Mark and Nathaniel.
Troooper Recke said the father, 36-year-old Chad Watson, and 11-year-old daughter Kylie, were at Vanderbilt University Medical Centre in Nashville. Mr Watson is in a critical but stable condition and Kylie is stable.