A woman died Tuesday shortly after she was found unconscious in a burning house in Southwest Roanoke County, a spokeswoman for the fire department said.

Firefighters were called to a two-story brick house in the 3400 block of Bunker Hill Drive, just off Brambleton Avenue, shortly before 2:30 p.m., said Roanoke County Fire and Rescue Chief Rick Burch.

They tried to enter the house through the front door, but the floor was collapsing because of the fire, Burch said.

When firefighters got into the house through a side door, they found the woman lying unconscious on the kitchen floor, overcome by smoke and suffering from some burns, Burch said.

Hilda Patterson, 65, was taken to Carilion Roanoke Memorial Hospital, where she later died of smoke inhalation, said fire department spokeswoman Jennifer Conley Sexton.

Patterson lived alone, Conley Sexton said, and no one else was in the house at the time of the incident.

Firefighters had the blaze under control in about half an hour.

Investigators determined Tuesday that the fire was caused by an electrical wiring failure in the basement. Most of the fire damage, which totaled about $70,000, was caused to the floor joists between the basement and the first floor. There was also significant smoke damage to the entire structure.

Jeri Campbell, 28, lives across the street and was going out to her car when she smelled and saw smoke coming from her neighbor's house. She said that she called for help and later watched from her driveway as medics carried the woman out on a stretcher and performed cardiopulmonary resuscitation.

"I was just praying that her daughter came and picked her up to go shopping or something," Campbell said.

Staff writer Neil Harvey contributed to this report.