According to Washington State Patrol, the eastbound 1999 Chevrolet Suburban was hit around 1:20 p.m. about 20 miles west of Leavenworth.
Driver Timothy Owen, 58, and front seat passenger Cheryl Owen, 56, were pronounced dead at the scene.
Two men and two women — all in their 20s — were injured and taken to Central Washington Hospital in Wenatchee.
The four were identified as Jeremy Owen, 22; Jamie Owen Mayer, 24; Steven Mayer, 24; and Jessica Owen, 27.
According to KOMO News, married couple Jamie and Steven Mayer were later airlifted to Harborview Medical Center in Seattle. Jeremy was treated and released from Central Washington Hospital but Jessica, a sixth-grade teacher at Frank Love Elementary in Bothell, remains in critical but stable condition.
State Patrol said trees snapping onto roadways have been a major problem on several highways throughout Washington as winter storms dumped heavy snow on much of the Cascades.
KOMO reported that Mount Baker Highway had recently reopened after being closed for three days due to heavy snow and 175 trees that fell across the roadway.