The crash happened about 5:08 a.m. on the freeway in the area of the 75th Street SE overpass, said trooper Mark Francis with the Washington State Patrol.
Witnesses at the scene said the man appeared to be trying to cross I-5. A driver in a Ford F-150 pickup truck saw the man and tried to swerve, Francis said.
The truck's passenger side mirror struck the man.
Another southbound car then struck the man, Francis said.
The man was taken to Harborview Medical Center in Seattle. Troopers were waiting on updated details from the hospital, Francis said.
The injured man was "very critical" but breathing, Francis said.
Troopers had not yet confirmed his age or hometown.
Traffic was backed up for about two hours, including surface streets in Everett as commuters sought alternate routes.
The investigation is ongoing.
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