Authorities identified the dead as a 40-year-old woman and nine people under 20, including two infants. Most of the younger ones were children or grandchildren of the woman, Kimberly Peterson.
Two members of the family escaped, including a young woman who jumped from the second floor and ran naked and screaming for help, officials said.
Fire Chief Kris Benson said the front of the house was ablaze when he arrived at 2:50 a.m. and tried to enter through a side door, but was forced back by smoke and flames.
"This fire had a very, very good jump on us," the chief said.
Jaime Hynds, a newspaper editor who lives across the street from the home, said she was awakened at about 2:30 a.m. by a naked woman shouting for help. The woman jumped from the second floor and ran to Hynds' home, according to her newspaper, The Courier-Express of DuBois.
The flames were so intense, they melted the siding on a neighboring house, reported The Courier-Express.
Peterson's husband, Douglas Peterson Jr., was at work in a nearby town when he learned about the fire. He arrived around 4 a.m. at the house on a main drag lined with several other single-family homes, officials said.
"We know everybody, so it's like losing one of your own," said William Hrinia, mayor of the rural town of about 2,000 set among rolling hills and farmland 80 miles northeast of Pittsburgh.
Many residents work at the town's glass manufacturing plants, Owens Brockway Glass Containers, now part of Owens-Illinois Inc. Doug Peterson Jr. worked for the company until a few years ago.
All 10 victims were found inside the house. State police identified them as Peterson; Rebecca Peterson, 17, and her daughter Kaylin Watson, 4 months; Douglas Peterson III, 13; Isaac Peterson, 8; Grace Peterson, 6; Lillian Peterson, 11 months; Dominic Delullo, 4, Desirre Delullo, 2, the children of Elizabeth Peterson, 20, who survived; and Jason Mowry, 19, a family friend.
James Peterson, 11, also survived, authorities said.
"They were a tight family and they all took care of each other. That's who they were and that's what makes it so sad," family friend Carol Paruso said, speaking through tears. "They liked to go to church and do family things."
Letter carrier Bill Fustini, who lives nearby and delivered mail to the home, said his dog woke him up around 2:30 a.m. When he saw the smoke, he called his son, a firefighter, who told him the home had gone up in flames.
"There was a little girl living in that house and she met me every day and she was the sweetest thing," Fustini said.
The fire's cause remains under investigation but is not considered suspicious. There were space heaters in the home, state police Lt. Scott Neal said. Authorities did not immediately know if the house had working smoke detectors.
Firefighters brought in wood beams to fortify the structure. The house's facade was charred, leaving a view of the inside of the home, remnants of a front porch and a lopsided stove. Two children's bicycles sat in the rubble.
Amy Glasl, principal of Brockway Elementary School, who grew up with Doug Peterson Jr., said he had come from a large family himself. Kimberley Peterson was a homemaker, she said.
Glasl said three children in the family attended her school; two died.
"They loved their kids, obviously. They had a lot of them," she said. "They didn't have a whole lot (materially), but they had each other and that's what made them happy."