The Washington State Patrol is investigating the cause of a serious three-car accident Friday afternoon that injured two Whidbey Island residents and closed Highway 20 for more than three hours.

The State Patrol reported that 40-year-old Ronald Leaver of Oak Harbor was driving a 2005 Mazda station wagon northbound on the highway. Near the intersection with Boon Road, Leaver crossed the centerline and stuck an oncoming 1996 Plymouth four-door car head-on.

The Plymouth, driven by 51-year-old Richard Sander of Greenbank, was propelled onto the southbound shoulder and struck a power pole.

Leaver’s car spun around from the impact and struck a southbound 1989 Mazda MPV minivan driven by 48-year-old Rob Schouten of Greenbank.

Sander was seriously injured. Ambulance crews transported him to Whidbey General Hospital, where he was airlifted to Harborview Medical Center in Seattle. He was in satisfactory condition Monday.

Leaver was transported to the Oak Harbor Naval Hospital for treatment. A hospital spokesperson said he was back at work Monday. Schouten was not injured.

The accident was reported at 3:05 p.m. The State Patrol and North Whidbey Fire and Rescue closed the section of Highway 20 and diverted traffic around the scene. The highway was re-opened at about 6:15 p.m.

Trooper W. Knudson said the road was closed so long because a special technician from the State Patrol must analyze such serious accidents. The technician mapped out the scene with detailed measurements.

Knudson said the State Patrol is interviewing drivers and witnesses to determine what happened, and specifically, why Leaver crossed the centerline. He said he did not know if troopers would issue any criminal citations.