SLIDESHOW: Violent Crash Closes Highway 18 VIDEO: 7 Hurt In Head-On Crash

Three people with minor injuries were taken to Overlake Medical Center. A fourth patient was taken to Valley General Hospital and two others were treated and released at the scene.

The seventh patient, who had to be cut from the wreckage, was transported in an Airlift Northwest helicopter to Harborview Medical Center. That patient's status was not immediately known.

The crash -- at Milepost 22 just west of Tiger Mountain Summit -- caused authorities to close all lanes in both directions.

Department of Transportation officials said the ramp from Interstate 90 to westbound state Route 18 was closed. Eastbound traffic was being diverted to Issaquah-Hobart Road.

Video from Chopper 7 showed smashed cars and debris strewn across the highway, with numerous fire engines and medic units at the scene.

Eastbound traffic was backed up almost five miles, officials said.