It happened on Little Naches Road, near State Route 410.
A man and woman from Burbank were traveling northbound when they drifted off the road and plunged into the Naches River.
The impact killed both people inside the truck.
Fast moving water carried the male passenger a mile-and-a-half downstream.
Action News has confirmed that the female passenger was 43-year-old Sherri Retterer.
She was traveling with 44-year-old William Retterer.
State patrol tell us the impact of the crash was so severe they still don't know who was driving the truck.