Four people were hurt, including two passengers who suffered major injuries, when a vehicle struck a tree on Petaluma Hill Road early Thursday, CHP officials said.

Driver Sierra Alli, 21, who recently moved from Healdsburg to Arcata, was arrested on suspicion of drunken driving and booked into Sonoma County Jail after being treated at Santa Rosa Memorial Hospital, Officer Jon Sloat said.

The collision occurred about 12:30 a.m. on southbound Petaluma Hill Road south of Snyder Lane.

Alli’s Volvo XC90 drifted off the roadway when she failed to negotiate a left curve in the road, Sloat said. The Volvo hit a tree at a high rate of speed, according to the CHP.

She and her sister Misha Alli, 22, who was in a backseat, got out of the vehicle with minor injuries, according to Sloat. Firefighters extricated front seat passenger Jordan Wachholz, 19, of Cloverdale and a passenger in the back seat, Benjamin Brock, 26, of Rohnert Park from the vehicle.

Wachholz and Brock were rushed to Memorial Hospital with major injuries that weren’t considered life-threatening, Sloat said. Officers at the scene noted Alli exhibiting possible signs of intoxication, leading to her arrest.

You can reach Staff Writer Julie Johnson at 521-5220 or On Twitter @jjpressdem.