One of the vehicles caught fire at the scene on Interstate 84 about 25 miles (40km) east of Portland on Thursday afternoon, but authorities said the occupants escaped unharmed.
Multnomah County Sheriff's Office said it believed "more than 100 cars, trucks and semi-trucks" were involved at several locations on the westbound I-84 near milepost 28.
There were reports of other drivers trapped and injured, with emergency services going car to car, but a police spokesman said no deaths had been reported.
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A pile-up reportedly involving more than 100 cars in "whiteout conditions" has closed part of a major highway in the US state of Oregon.
