A fire in the rural Kentucky town of Greenville killed eight children along with their mother on Thursday morning, leaving the father and one daughter in critical condition, the Assocaited Press reported.

According to Kentucky State Police Trooper Stu Recke the fire began due to combustible material against an electric heater. The temperatures on the night before and morning of the fire were in the single digits, according to the AP.

The bodies of the eight children and their mother were found huddled together and were identified as 35-year-old LaRae "Nikki" Watson, 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, according to the AP.

Trooper Recke said they might have been all in one area trying to escape through a window, but officials are still not sure and autopsies on the bodies began late Thursday, the AP reported.

The two surviving family members are the father, 36-year-old Chad Watson, and his 11-year-old daughter Kylie Watson, the AP reported. Both are being treated for critical injuries at Vanderbilt University Medical Center in Nashville, Tenn. but are in stable condition.

First responders who lived nearby in the town of about 4,000 people said the house was covered in flames by the time they arrived, according to the AP.

Ricky Keith, a family member who lives a mile up the road from the Watson family said they had been struggling financially for years, and the father had two jobs while the mother stayed home with the kids, the AP reported.

"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 told the AP.