The children's grandfather, Noah Sauder, has told The Associated Press that he thinks the blaze may have started in the kitchen, where the family used a propane heater.
The victims were ages 7 months old to 11 years old. A coroner says the children died of smoke inhalation in Tuesday night's fire, which started while their mother worked in the barn and their father made rounds in a milk truck. A 3-year-old girl escaped.
Funeral services will likely be next week.
The blaze tore through the home, exposing the interior and scorching the front, rear and side. A car parked beside the house was burned to the bare metal, its windows shattered.
Public records indicate the parents are Theodore and Janelle Clouse. A neighbor described the family as hard-working.
Police said the children's father had left the two-story home on a working farm in dairy country not far from the state capital, to begin his rounds hauling milk around 10 p.m. Tuesday. Two children, ages 2 and 3, were watching television at the time.
The father picked up milk and then parked the truck about a mile from home before nodding off, state police Trooper Tom Pinkerton said.
Soon after, the 3-year-old smelled smoke in the home and ran to the barn to alert her mother, who apparently tried to get into the house. The woman then ran to the homes of two neighbors before getting someone to call 911, then ran with the child to the father's truck and banged on its windows, screaming that their home was on fire, he said.
By the time the father returned to the home it was fully engulfed by flames, Pinkerton said. Firefighters had arrived and were battling the blaze at the charred home.
The Perry County coroner ruled the children died of smoke inhalation, Pinkerton said. Officials said they were six girls, ranging in age from 7 months to 11 years old and a 7-year-old boy.