AUBURN, Wash. -- A man driving the wrong way on Highway 18 caused a head-on crash that left another driver seriously hurt and closed westbound lanes of the roadway Thursday morning.

The accident happened at 3:19 a.m. near Peasley Canyon Road in Auburn, firefighters said.

The driver of a Subaru was struck head-on by a Toyota. The driver of the Toyota, a 25-year-old Idaho man, drove about 1 1/2 miles the wrong way on the highway before the collision.

The driver who caused the crash is under investigation for vehicular assault because alcohol is believed to be a factor in the collision, troopers said.

The Subaru's driver was trapped in the car for about 30 minutes as firefighters worked to pull him free. He was taken by helicopter to Harborview Medical Center in Seattle.

The Toyota's driver was treated for minor injuries and was taken to Auburn Regional Medical Center for evaluation.