A mattress on the roadway led to a semitruck-vs.-car fatality crash on Interstate 5 in Mountlake Terrace Saturday morning, and the Washington State Patrol is searching for a pickup truck that lost the mattress just prior to the crash.

State Patrol spokesperson Trooper Jacob Kennett said the state patrol received a call at 6:35 a.m. Saturday regarding the mattress, which had fallen off the truck near the 220th Street Southwest exit.

Shortly after, at 6:38 a.m., a silver Nissan sedan struck the mattress — which was located in the third lane next to the carpool lane — swerved to the right, then swerved left in front of a semitruck. The semi struck the Nisssan on the driver’s side door, and the driver — who has not been identified — died at the scene, Kennett said.

Interstate 5 was blocked northbound at the 220th Street exit for several hours while state patrol detectives investigated the crash. The roadway was reopened around 12:30 p.m.

The truck is described as a small, older, dark-colored pickup with wood-sided bed racks carrying miscellaneous household items. Anyone with any information about the truck or its occupants is asked to contact the Washington State Patrol Detective Dan Komnick at 360-654-1204