It happened on highway 12 near McDonald road. Washington State Patrol says a 60-year-old Walla Walla man was driving westbound when he started drifting off the road. He then hit a tree.
They're not sure if he fell asleep at the wheel or if there was a medical problem.
It does not appear alcohol or drugs played a role. The man's name was not released. He was not wearing a seatbelt.