Amy Lynn O'Brien, 37, who called police and told them she'd turn herself in at 4 p.m. Wednesday, surrendered herself approximately 24 hours later, at 4:25 p.m. Thursday.
Wednesday's crash took place near Chief Sealth High School in the 2600 block of SW Thistle Street just after 10 a.m.
"All of a sudden you hear, 'Boom! Boom!' " said witness Thomas Terry. "And I see two bodies just fly up in the air; the car just drove off like they didn't even care. It had to be going at least 60, 65 (mph)."
The victims, 18-year-old Cassandra Goodwin and her 17-year-old friend, were taken to Harborview Medical Center. Goodwin was originally listed in critical condition but was upgraded to serious condition later Wednesday and was expected to make a full recovery.
Police and witnesses say it started with an argument over the driver's dog.
"The dog jumped on Cassandra. Cassandra hit the dog," said family friend Chelsea White.
Witnesses say the woman became angry when she thought Cassandra hit her dog, who'd gotten loose from her home across the street from the school.
"(Goodwin) apologized after she hit the dog," White said.
The woman and the girls argued, and witnesses say the woman then upped the ante.
"She brought out a Taser chased us with a Taser," White said.
The victims' friends say the girls ran towards the high school.
"(The driver) came around the corner -- she purposely drove her car a certain way so she could hit Cassandra," White said.
The woman drove away after the crash in a black Honda and remained at large until she turned herself in.
After turning herself in, the O'Brien was interviewed by detectives and subsequently booked into the King County Jail for felony assault.