An 18-year-old was seriously injured this morning when her car collided with a semi truck on I-90 Friday morning.

At 10:17 a.m., a semi truck and trailer struck the driver’s side of the teenager’s red Toyota Camry just east of High Point, between Issaquah and Preston. The driver of the Toyota is being treated for life-threatening injuries at Harborview Medical Center in Seattle.

The driver of the semi was physically uninjured but very shook up emotionally, Washington State Patrol Sergeant Tina Martin said. The semi truck was badly damaged and was towed.

Washington State Patrol detectives are still working to figure out how the accident occurred.

“Some reports say a third vehicle may have cut over and caused the Toyota to lose control,” Martin said. However, she said, it may also have been a reaction on the part of the Toyota driver.

The Toyota had swerved and gone across lanes, and was sideways when hit by the semi. The car came to rest across the right and center lanes, and the truck ended up on the shoulder, Martin said.

The crash closed all eastbound lanes on I-90 for two hours.

Martin said that allowing proper “following distance is very important,” as is “making sure you’re aware of what other drivers are doing.”

If you have any information about the crash, please call Detective Russ Haake at 425-410-7717.