The three teenagers killed early Wednesday morning when their SUV crashed into a parked semi-trailer near Lynnwood were identified Thursday.

The Snohomish County Medical Examiner listed the victims as 16-year-old Travin Nelson, Landon Staley, also 16, and 15-year-old Mikayla Sorenson. All three went to Mill Creek's Jackson High School.

A fourth teen in the car, 15-year-old Kiley O'Laughlin who attended Cascade High School, remained in serious condition Thursday at Harborview Medical Center's ICU.

A small memorial has grown at the crash scene.

Lynn Gutierrez and her daughter Kalona came to pay their respects. Kalona knew the kids who were killed.

"Oh, my God," she said. "I mean, how is it possible?"

The four teens crashed into a truck trailer parked the wrong way along Alderwood Mall Parkway. It's unclear what happened in that car before the crash, but it was around 4 a.m.

Police say speed may have been a factor - an apparent summertime joyride ending in the worst possible way.

"You're all in the car having fun. It's so easy," said Gutierrez. "It's a joy ride, but look what happened."

Friends say the teens were coming back from Seattle and had been posting Snapchats just an hour before the accident.

Gutierrez said this tragedy is inspiring her to have candid talks with her daughter about making good decisions, as she struggles with how much freedom to allow.

"As a parent, all I want is for her is to come home. That's every parent's wish is for them to just walk through that door," said Gutierrez.

Several dozen students gathered at Jackson High throughout the day Thursday to meet with counselors and process their grief.

Among them was Lauren Crossley, a friend of Mikayla.

She's learning a terribly hard lesson with consequences that are so painfully real.

"You have to be conscious of who you're driving with and hanging out with," she said, tears streaming down her cheeks. "You have to think through things before you do something because it doesn't just affect your life, but those of others left behind."