A Montesano woman was killed in a car accident Monday afternoon that caused traffic backups for at least three hours on State Route 12, just east of Aberdeen.

According to the Washington State Patrol, 87-year-old Patricia Eaton was driving from Aberdeen Lake Road making a left turn onto the highway heading east in a 2002 Subaru Outback.

As she pulled out, a 57-year-old Humptulips man driving west on the highway in a 1993 Ford F-250 pickup truck was unable to stop and collided with the Subaru, the State Patrol report says.

Both vehicles were total losses and the Montesano woman was pronounced deceased at the scene. The pickup truck’s driver was treated for injuries and released, the State Patrol said.

The westbound lanes were closed for 3 hours and 25 minutes according to the report, and cars alternated using the eastbound lane, causing additional traffic as Patrol officers conducted an investigation.

The State Patrol report says the cause of the accident was failing to yield right of way by the Subaru’s driver.