PORTLAND, Ore. - Heavy rain and flooding, already blamed for three deaths in the Pacific Northwest, washed out a major highway near Mount Hood and forced the shutdown of 67 miles of the North Cascades Highway in Washington state Thursday.

The White River flowed over Oregon 35 on Mount Hood's eastern flank on Monday and Tuesday, cutting 20-foot-deep ruts through the road and sending boulders and trees rolling down the mountainside, said Bill Barnhart, an Oregon Department of Transportation manager.

Two creeks also wiped out a section of the same highway to the north, Barnhart said. Reopening the highway near Mount Hood is estimated to take $20 million.

The storms damaged hundreds of homes and broke rainfall records. At least three deaths were blamed on the flooding: two men swept into a Washington river and a 78-year-old woman found along the Oregon coast, where another woman was missing.

Rescue teams also continued to search for hunters who might be trapped in the southwest Washington hillsides between Mount Rainier and Mount St. Helens, officials said Thursday.

Floodwater from swollen creeks and rivers damaged roads and destroyed campgrounds at Mount Rainier National Park, closing it for the first time since 1980 when Mount St. Helens erupted. Superintendent Dave Uberuaga said it would be at least several weeks before the park reopens to visitors.

Washington authorities decided to shut down the stretch of North Cascades Highway on Thursday because of concerns about the stability of the ground under the roadbed.

On Mount Hood, as much as a million cubic yards of rock, mud and sand covered a quarter-mile stretch of road, the main highway connecting U.S. 26 from Government Camp to Hood River, Barnhart said.

"None of us at ODOT or the U.S. Forest Service have ever seen it this bad," Barnhart said. "Our biggest concern right now is the safety of our workers."

There were no estimates when the highway would reopen. The same highway washed out in the summer of 2005.

More rain was expected Friday and over the weekend, but "just a rainstorm, not a flooding rain," said forecaster Chris Burke at the National Weather Service. While river levels were dropping, some were still at flood stage, with recovery and damage assessment still days away.