Kentucky State Police Trooper Stu Recke said 35-year-old LaRae "Nikki" Watson and her children were found in the master bedroom of the home, part of which had collapsed during the blaze. Recke said that could be an indication they were trying to escape through a window, but investigators weren't sure.
Relative Ricky Keith described the Watsons as a loving couple who worked hard to provide for their children.
"I don't know how they made it as long as they had. They've struggled as long as I've known them, but they loved one another, I know that and they loved them kids," Keith said.
Along with Nikki Watson, the remains of 15-year-old Madison Watson, 14-year-old Kaitlyn Watson, 13-year-old Morgan Watson, 9-year-old Emily Watson, 8-year-old Samuel Watson, 6-year-old Raegan Watson and 4-year-old twin brothers Mark and Nathaniel Watson were retrieved from the burned-out structure by Thursday afternoon.
Chad Watson and Kylie Watson remained hospitalized Friday morning at Vanderbilt University Medical Center in Nashville, Tenn., in critical but stable condition.
Investigators say the fire in the community of Depoy, just west of Greenville and about 130 miles southwest of Louisville, started when a combustible material fell against an electric baseboard heater.
Recke said the nighttime temperatures dipped into the teens and single-digits. There's no indication of foul play, he said.
Muhlenberg County Judge-Executive Rick Newman said grief counselors would be meeting with first responders Friday. School Superintendent Rick McCarty said counselors were being made available to students and staff.
Recke described the region as "a rural area where everybody knows everybody." The house is in a small neighborhood of single-family dwellings, trailers and farmland.
"The whole county is close. You've got a very small community, everybody knows everybody," Newman said. "They know their business, their hardships, the whole deal."
The side and roof of the small, white-wood frame house with three bedrooms and an enclosed porch collapsed around the chimney. In front of the house, a white van stood on a concrete parking pad. At least five kids' bikes and a child's riding toy were strewn about the yard near a swing set.
Keith said the home was "wore out" and the children played constantly outside.
"They kept them in the yard and didn't let them out of their sight," Keith said.
Several first responders lived near the home and reported that the house was fully engulfed when they arrived within minutes of getting the call, Recke said.
Newman said he worries about the neighbors and first responders in the area. While the county had seen coal miners die, the deaths of nine family members is nearly unheard of.
"This is a strong community," Newman said. "But, man, I'm telling you, it's difficult."
Thursday's blaze was Kentucky's third fire in a little more than a year that has killed five or more people. Last January, four children under 6 and their father were killed in a blaze near Pikeville in eastern Kentucky that also severely burned their mother. Authorities said the home lacked a smoke detector.
In March, a fire at a home in the southern Kentucky community of Gray killed a young couple and five children, the oldest of whom was 3.