KOMO-TV reported Saturday's incident was the second serious accident caused by a tree falling over the highway because of heavy snow on the pass.
On Friday, a Bothell couple was killed and their four adult children were injured when a tree came down on their SUV.
In the most recent incident, a tree came down about 5:50 p.m. Saturday, about 22 miles west of Leavenworth.
All five people inside the vehicle were injured, some of them seriously. The State Patrol said three adults and two children were all taken to area hospitals.
U.S. 2 is closed from milepost 64 at the summit to milepost 99 at Leavenworth.
Transportation spokesman Jeff Adamson said Monday there's no estimate for when that section of highway will reopen.
The ski area is open from the west. The roadway will remain closed as crews work to clear the tree debris.
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