The driver of a vehicle that rolled downhill, hitting and killing a 12-year-old girl by her Central District middle school, has not been arrested.

The Washington Middle School student was standing on the sidewalk and was going to recess with other classmates Thursday afternoon when the empty SUV rolled about 75 yards downhill and fatally struck her.

The driver, a 51-year-old woman, was evaluated by two police drug recognition experts who both said she did not appear to be impaired, Seattle police spokesperson Detective Brian Pritchard said. She was driving a GMC Acadia.

“We believe that the vehicle was rolling backward, the driver having failed to place it completely in park,” Seattle Police Department Assistant Chief Todd Kibbee said outside the school on Thursday. “This is obviously a tragic situation for the community here.”

Detectives and prosecutors will determine if charges are going to be pursued, Pritchard said.

“Especially (with) such a high profile case, they’re going to definitely take their time on something like this,” he said.

As the investigation is ongoing, Pritchard declined to release any additional information. School officials said they would not publicly identify the girl.

In addition to the student who died, two others were involved in the incident, Pritchard said. One suffered minor abrasions to the leg and the other was not hurt, he said.

About 60 students held a “memorial walk” in their classmate’s memory outside of Washington Middle School on Friday, according to the district. Superintendent Brent Jones and School Board President Gina Topp also visited teachers, staff and students, and counseling and other mental health support services were made available. The assistance and additional resources will continue next week, the district said.

“The tragic death of one of our sixth graders has had a profound impact on students and staff,” the district said in a statement on Friday afternoon. “We are heartbroken and stand in solidarity with the student’s family while they mourn the loss of their loved one. … At this time, our focus remains on ensuring students and staff have a safe, welcoming place to be as they process this devastating incident.”

The district said it will continue to work with the authorities during the investigation. Students were dismissed early on Thursday.

A Washington Middle School student said he had just left the school’s entrance for his lunch break when he heard screaming. “I looked back, and I saw my assistant principal crying and screaming,” he said.

He turned to walk toward the commotion when he saw what looked like an SUV reversing, he said. A group of people clustered around a student on the ground and a woman ran toward the girl’s body, crying, he said.

“It feels horrible and like no kids should have to witness that or go through that,” he said. “It’s just really sad.”