The Guilford County fire marshal said a space heater ignited combustible materials in the home's living room. The children were sleeping in a bedroom next to the living room, officials said.
The house did not have a working smoke detector or residential sprinklers, said Mike Wright, deputy director of Guilford County Emergency Services fire division.
The children's bodies were taken to the medical examiner's office in Chapel Hill for autopsies.
Their grandfather, Fred Ridge, was at home with them at the time of the fire and tried to rescue them, Wright said. He suffered burns to his hand and his hair was singed, Wright said. Paramedics treated him at the scene, but he refused to go to the hospital.
The status of the passers-by who stopped to help was unclear Saturday.
Emergency officials received multiple calls about the fire beginning at 6:48 a.m. About 50 percent of the nearly 1,000-square-foot single-story home was engulfed in heavy flames when the first firefighters arrived, Wright said.
Fred Ridge awoke to the fire and tried to get inside the children's bedroom, where they were sharing a bed, Wright said. But he was unable to get to them because of the flames.
Ridge went outside to the children's bedroom window, where he and the two passers-by used yard tools to try and pull their bed to the window so they could grab the children. The flames forced them from the window, Wright said.
The children were pronounced dead at the scene.
About 35 firefighters from six different departments responded to the fire. The house is a total loss, Wright said.
Wright identified the children's mother as Dana Ridge, who was not at home when the fire started. The Ridge family gathered at a house next door on Saturday afternoon, where neighbors said the children's great-grandfather lives. A man in the front yard said the family did not want to comment.
Neighbor Ned Roney recalled Matthew as being tall for his age. Roney said Matthew wandered in his yard once several months ago to play with his dog. Roney's wife gave Matthew cookies before a family member came to pick him up.
"It's terrible," Roney said of the deaths. "You can't get no worse."
Written by News and Record