The fire started at 201 Kate Smith St. about 8 a.m., police said.
Neighbors reported seeing a flash and hearing a boom, indicating lightning might have struck the house, but that has not been confirmed, Workman said.
Lynnwood Holloway, a close friend of the victim, identified her as 85-year-old Billie Marie Kidd.
"I just can't get this in my mind that something like this has happened," Holloway said. "So fast, so soon. To be over here yesterday evening and to have talked to her at 8:30 or 9 last night on the telephone, like nothing has happened. But I guess it can change at the drop of a hat."
Kidd's brother, Bryan Reed, said he got a call from his sister saying her house was on fire and to hurry and get there. But when he arrived it was too late and the house was too hot, Reed said.
Reed said his sister suffered from Parkinson's Disease and could not see very well.
Prairie Grove police, Prairie Grove fire crews and the Lincoln and Farmington fire departments responded, Workman said.
By 10 a.m., fire crews had department, but the Washington County Fire Marshal and officials from the Washington County Sheriff’s Office remained at the site, investigating the cause of the fire.
Stay with 5NEWS for more on this developing story.