The driver of an SUV that crashed into a semi-trailer on Alderwood Mall Parkway in July was under the influence of THC at the time of the collision, according to a report released Friday by the Snohomish County Sheriff’s Office.

The crash killed three teens and seriously injured a fourth when the SUV collided with the semi-trailer, which was parked the wrong direction, on July 26 about 4 a.m.

Blood samples show the driver had a THC level of 6.8 ng/mL, according to the sheriff’s office. The legal limit for people over 21 years old is 5 ng/mL, but the legal limit for people under 21 is 0, which the driver was.

THC is the chemical compound in cannabis.

The driver was speeding, inexperienced, and likely fatigued due to the time of day, according to the lead detective on the case. Detectives determined the SUV was traveling at 56 miles per hour just before the crash.

The driver also violated their Intermediate License by driving other passengers under 20 years old and operating the vehicle between 1 a.m. and 5 a.m.

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<p><span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 14px;">(From left to right) </span><span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 14px;">Travin Nelson-Phongphiou, 16, </span><span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 14px;">Mikayla Sorenson, 15, and </span><span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 14px;">Landon Staley, 16.</span></p>

Landon Staley, 16, of Everett, Travin Nelson-Phongphiou, 16, of Everett, and Mikayla Sorenson, 15, of Bothell, died from multiple blunt force injuries. Kiley O'Laughlin, 15, was seriously injured.

Staley, Nelson-Phongphiou, and Sorenson were all students at Jackson High School, and O’Laughlin attended Cascade High School.