The bizarre incident unfolded Wednesday at about 2 a.m. when a gold-colored car heading east on Highway 518 burst into flames just east of the Sea-Tac Airport exit.
The driver of the car did not pull over but jumped out of the moving vehicle as it was going at about 60 mph.
A taxi driver spotted the man lying on the pavement. He stopped to help and called 911.
Meanwhile, the burning car kept going with no one inside for about a mile and half before crashing into some bushes, said a state trooper at the scene. A fire truck responded and doused the flames with foam.
The driver who jumped sustained a broken ankle, some burns and some scrapes. He was walking and talking just after the accident, then was taken to Harborview Medical Center, where he is listed in serious condition in the intensive care unit.
The driver told troopers at the scene that he jumped out of car because it was on fire. But investigators still don't know why he bailed out of the car instead of stopping.
There is no indication of drug or alcohol use, but the State Patrol will be investigating.
The car is registered to the driver. Investigators are inspecting the vehicle to see where the fire started.