Mary Garvey, 90, was last heard from around Thursday around 5 p.m., but was not reported missing until around 24 hours later, Haggard said.
Police immediately began a search, but there were no results until shortly before 1 p.m., when her vehicle was located at the bottom of a ravine off of Orinda Woods Drive near Village Gate Road, Haggard said.
Garvey's body was located inside the vehicle.
The cause of the crash remains under investigation.
Garvey was described as a very lucid and active woman who still had her driver's license and visited friends regularly, Haggard said.
However, it was unusual for her not to call someone when she was going out to tell them where she was going.