An unidentified woman was killed Saturday morning when the car she was riding in went off the road in Napa County and struck a tree in an apparent drunken driving crash.

The driver was arrested on suspicion of driving under the influence and vehicular manslaughter, the CHP said Sunday.

Bobby Recinos, 21, of Lower Lake was driving a 2006 Dodge Charger southbound on Highway 29 at Tucker Road just before 4 a.m., the CHP said.

Recinos failed to negotiate a sweeping curve and the car went onto a dirt shoulder, striking a tree, according to the CHP.

The woman in the front passenger seat wasn't wearing a seat belt and died at the scene. Her name was withheld pending notification of kin.

The other three occupants were wearing seat belts and suffered injuries from minor to major, but none life-threatening, the CHP said.

Recinos and passenger Israel Perez, 32, of St. Helena were transported to Santa Rosa Memorial Hospital, where Recinos was treated for minor injuries and Perez was treated for major injuries.

Passenger Olga Rojas, 29, of Napa was transported to Queen of the Valley Hospital in Napa with moderate injuries.

Recinos was booked into Napa County Jail on suspicion of vehicular manslaughter while intoxicated and driving under the influence of alcohol or drugs.

The CHP is asking any witnesses to the collision call 253-4909.