The lawsuit alleges that the district and Fairfax Hospital failed to take steps to prevent the brutal stabbing, which took place Oct. 24, 2011, in a Snohomish High School bathroom.
The stabbing victims, both girls aged 14, were both stabbed several times with a kitchen knife wielded by another girl, aged 15.
One of the victims, April Lutz, was stabbed more than a dozen times and nearly died from the attack, according to the lawsuit. One wound came within a half inch of a crucial artery and her heart stopped at least twice on the way to the hospital, according to her doctors.
The second student, Becka, also was stabbed multiple times, resulting in severe wounds to her back and arm that required many stitches, according to the complaint.
"The victims' wounds were very serious, and the emotional scars of this brutal attack run even deeper," said attorney Sim Osborn, who is representing the families of the victims.
Osborn called the stabbings a "preventable tragedy." He said the school and the hospital knew that the girls' attacker harbored violent impulses, yet they allowed her to have "free reign on campus."
"The defendants failed to act to protect students and the public," Osborn said.
The girls' attacker was charged with first-degree attempted murder and second-degree assault. In March she pleaded guilty to charges under an agreement in which she will serve a total of 13 years in incarceration.
The lawsuit, filed Thursday in King County Superior Court, alleges that both the school district and Fairfax Hospital were negligent, failing to protect students despite obvious signs that the assailant was dangerous.
According to the lawsuit, the assailant had told a school counselor as early as April 2011 that she was having violent fantasies involving injuring and killing people. The lawsuit states that she became obsessed with a female student and threatened to kill that girl's boyfriend, causing the district to expel her from school.
She was then admitted to Fairfax Hospital in Kirkland, where mental health professionals monitored her behavior. She was released and allowed to return to school in early May, according to the lawsuit.
The lawsuit names as defendants the Snohomish School District, Fairfax Hospital and the parents of the attacker. It follows the filing of an administrative claim. The case will now proceed toward discovery and then a jury trial.