A 50-year-old driver who struck two teenage girls -- killing one -- in Oakley Tuesday was arrested on suspicion of driving under the influence, police said Friday.
Kristina Salvitti, allegedly exhibited signs of being under the influence after a collision at about 2:45 p.m. on East Cypress Road near Bethel Island Road, police Lt. Eric Navarro said.
Salvitti was the driver of a station wagon that struck two girls, leaving both critically injured, Navarro said.
Fifteen-year-old Roshel Madlangbayan died at the scene. Her friend, 17, was flown to Children's Hospital in Oakland. An aunt said they were going to a park to hang out.
Navarro said the girls were walking along the shoulder of a rural road that has no sidewalks. It's often used by pedestrians but is not considered a safe route for walking, he added.
The girls were all the way on the road's shoulder and were only hit because Salvitti allegedly swerved right in her station wagon for a still undetermined reason, Navarro said.
The station wagon then went over a curb and traveled through a field before coming to rest roughly 150 yards away, Navarro said.
During initial contact with Salvitti, officers suspected that she was possibly intoxicated, Navarro said. She was also driving with an expired driver's license.
Although police arrested the woman, investigators and the Contra Costa County District Attorney's Office are awaiting the results of toxicology tests, which could take more than two weeks.
No formal charges have been filed against the woman as of Friday morning, according to the district attorney's office.
Salvitti, who Navarro said was living out of the station wagon involved in the collision, was booked into the Martinez Detention Facility but is no longer being held there, according to the jail's record system.
A roadside memorial has cropped up where Roshel was killed.
"She’s my best friend," Roshel's cousin King Madlangbayan said during a memorial this week. "She’s a very big part of my life, a special place in my heart, and she will never be forgotten."
NBC Bay Area's Ian Cull and Cheryl Hurd contributed to this report.