Washington State Patrol is investigating the Dec. 4 accident on Interstate 90 at S.R. 18, and encouraging people who may have witnessed the reported erratic driving of the white van to report what they saw.

The accident, which backed up evening commuter traffic for at least two hours, was reportedly caused by the van, being driven by Tyler O. Riley, 27, of North Bend.

According to witnesses, at 3:42 p.m., the white van was eastbound and driving erratically prior to the collision; the driver failed to observe that traffic was coming to a stop near the freeway exit. The van did not slow down in time and did not complete a lane change in time, but instead struck the rear end of the vehicle ahead, a 2013 Mini Cooper, and two other vehicles.

The Mini Cooper ended up in the ditch. The driver was conscious but had sustained serious injuries according to the State Patrol report. The other two vehicles were damaged but the drivers sustained only minor injuries.

Riley, whose vehicle had stopped across lanes 2 and 3 of the highway with heavy front-end damage, was uninjured. Troopers arrested him for Vehicular Assault due to the nature of the injuries and signs of impairment that they observed.

Detectives are seeking any additional witnesses to the erratic driving of the white van prior to the collision. Contact Detective Mauro at (425) 401-7746 or by email at victoria.mauro@wsp.wa.gov if you have additional information.