Two people escaped, including an adult daughter who jumped from the second floor and ran naked and screaming for help, authorities said.
The fire was not considered suspicious, though it remained under investigation. Space heaters appeared to be in use, state police Lt. Scott Neal said.
Kimberly Peterson died along with five of her children, ages 11 months to 17 years, authorities said. Her husband, Douglas Peterson Jr., was at his job in a nearby town at the time.
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.
Authorities did not immediately know if the house had working smoke detectors. All 10 people were found inside the house.
State police identified the other victims as Rebecca Peterson, 17; Douglas Peterson III, 13; Isaac Peterson, 8; Grace Peterson, 6; Lillian Peterson, 11 months; Cailyn Watson, 4 months; Domanic Delullo, 4; Desirre Delullo, 2; and Jason Mowry, 19.
The survivors are Elizabeth Peterson, 20, and James Peterson, 11, authorities said.
"We know everybody, so it's like losing one of your own," said William Hrinya, mayor of the rural town of about 2,000 people, which is set among rolling hills and farmland 80 miles northeast of Pittsburgh.
The three generations lived together in the home, said family friend Carol Paruso.
Elizabeth Peterson lost two of her children in the fire, Desirre and Domanic Delullo. Cailyn Watson was Rebecca Peterson's daughter. Mowry was a family friend.
"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," Paruso said, speaking through tears. "They liked to go to church and do family things."
The children often rode their bikes on the side street, lined with several other single-family homes, neighbor Lori Anderson said.
An overturned tricycle sat by the front door after the fire, while two scorched vehicles were in the driveway. Meanwhile, the ravaged front section of the house revealed a lopsided stove where the porch once stood. The roaring flames melted the siding on a neighboring house.
Jaime Hynds, a newspaper editor who lives across the street, said she was awakened at about 2:30 a.m. by Elizabeth Peterson, her newspaper, The Courier-Express of DuBois, reported. The woman had jumped from the second floor and run to Hynds' home.
Douglas Peterson Jr. learned about the fire on the job and arrived home at about 4 a.m., officials said. A neighbor said he works at a factory in nearby St. Marys.
Many residents work at the town's three glass-manufacturing plants, Owens Brockway Glass Containers, now part of Owens-Illinois Inc. Doug Peterson Jr. had worked for the company until a few years ago.
Amy Glasl, principal of Brockway Elementary School, said three children in the family attended her school. Two of them died.
"They loved their kids, obviously. They had a lot of them," Glasl said. "They didn't have a whole lot (materially), but they had each other and that's what made them happy."
The small school district of just about 1,000 students has been hard-hit by the tragedy, Glasl said.
Glasl, who grew up with Doug Peterson Jr., said he had come from a large family himself. Kimberly Peterson was a homemaker, she said.
Letter carrier Bill Fustini, who lives nearby and delivered mail to the home, said his dog woke him up at about 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.
Denise Carlini, principal of Brockway's junior-senior high school, knew the entire Peterson family and Jason Mowry, the family friend who also died in the fire. She recalled 17-year-old Rebecca's red hair, 13-year-old Douglas' laughter and 19-year-old Mowry's hopes and dreams for the future.
Douglas loved history and was looking forward to the start of the fishing season, Carlini said.
"He's very well liked by his teachers. They were very stricken today because he was a hard worker, he was a good kid," she added.
Mowry left school Wednesday excited about a 98 he had scored on an English speech.
"His teacher ... said this was the highest grade he ever got on an assignment like that, so he was going to go home and tape it up," Carlini said.
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Associated Press writer Ramit Plushnick-Masti in Pittsburgh
contributed to this report.
