A 44-year-old man from Vancouver, Wash., died in a one-car accident Friday afternoon on Interstate 405 at exit 18 in Kirkland.

Washington State Patrol trooper Julie Judson said the man was traveling north in the exit lane when witnesses saw his vehicle “suddenly drive off the roadway and hit the pole of the exit sign.”

The car then caught on fire and was “completely engulfed in flames” soon after.

Other commuters pulled the man out and performed CPR, said Judson. The cause of his death is unknown but Judson speculates it could either be from a medical condition or the impact of the crash. The driver was not wearing a seat belt, Judson said.

The accident occurred around 2:20 p.m. and traffic stayed backed up into the evening.

Judson said at around 5 p.m. they were still in the process of removing the vehicle from the pole and towing it off the ramp. She said the car was so damaged that they would have to use a flatbed truck to remove it.