A house fire that killed a 61-year-old woman in San Francisco's Ingleside Heights neighborhood on Wednesday night is considered accidental, a fire department spokeswoman said Thursday.

The one-alarm fire was reported at 8:35 p.m. in the first block St. Charles Avenue.

An off-duty fire department employee who lives in the neighborhood called to report smoke in the area, and firefighters responded and located the fire, department spokeswoman Mindy Talmadge said.

The woman who died in the fire, identified by the medical examiner's office as Dean Wernet, was the lone occupant of the home, Talmadge said.

While the fire is believed to have been accidental, its cause remains under investigation, according to Talmadge.

The blaze, which was extinguished at 9:13 p.m., caused an estimated $75,000 in damage to the home and $15,000 in damage to its contents, she said.