Nincy Flores Cruz was arrested after the accident, which occurred at about 10:50 p.m. on N. McDowell Boulevard just north of Professional Drive near the Petaluma Valley Hospital, according to police.
Cruz allegedly was driving a white 1994 Buick sedan northbound on N. McDowell Boulevard when the vehicle collided with a tree in the center median and came to rest in the southbound lanes of the street.
Arriving officers and paramedics found the female passenger trapped in the vehicle and she was pronounced dead at the scene. The victim's identity is being withheld pending the notification of next of kin, police said.
Cruz sustained a minor injury to her finger and was transported to the hospital.
She was later determined to have been driving under the influence, and was arrested. Police also discovered that she was driving without a license.
Cruz was booked into Sonoma County Jail with bail set at $50,000, according to police.
The accident is still under investigation and police are looking for witnesses. If anyone observed the crash, they are asked to call Traffic Officer Walt Spiller at (707) 781-3720.