Palo Alto woman Alexandra Souverneva is suspected of lighting a fire near where the Fawn Fire started, Cal Fire announced on Thursday.
Employees working near the JF Shea and Mountain Gate Quarries reported seeing a woman trespassing at the property and acting irrationally.
Later in the day, authorities believe that the same woman, 30-year-old Palo Alto resident Alexandra Souverneva, emerged from the brush near the fire line and approached fire crews for help.
Souverneva is now accused of starting the fire, although it is unclear how. She has been arrested and is facing arson to wildland charges.