PORTLAND, Ore. – Slick roads and whiteout conditions caused by a winter storm led to a multi-vehicle pile-up involving more than 20 cars, trucks and semi-trucks in northwest Oregon on Thursday.The crash occurred on Interstate 84 near Multnomah Falls, which is located nearly 30 miles east of Portland. In an initial social post, deputies with the Multnomah County Sheriff’s Office estimated over 100 vehicles had crashed. “An SUV caught fire in the pileup on I-84, that’s described by deputies as involving more than 100 cars, trucks and semi-trucks,” the Multnomah County Sheriff’s Office said. “Everyone was able to get out of the SUV. Responders are going car by car. There are reports of injuries; no number at this time.”However, the sheriff’s office later corrected the tally to around 20-30 vehicles, saying the harsh weather conditions hindered getting a more accurate count. “After a more thorough assessment by responders, the current estimate is that 20-30 vehicles were involved in the crash on I-84 west of Multnomah Falls,” the sheriff’s office said. “Low visibility made it difficult to differentiate initially between vehicles that were involved and vehicles that were only stopped.”The freeway remains closed. A nearby weather station indicated over 4 hours of steady snow, winds gusting over 25 mph and visibility of 1/4 miles or less.Other crashes, including another one involving more than 20 vehicles, were reported elsewhere in Multnomah County. DANGEROUS ICE STORM THREATENS OVER 1 MILLION IN PACIFIC NORTHWEST: ‘THIS HAS US CONCERNED’Across the border in Washington, the weather was no better. Officials in Clark County, home to Vancouver, reported multiple crashes, as snow was causing low visibility and slick roads, according to the Washington State Department of Transportation.Another 15 vehicles, including multiple semis, also collided in the snow-covered southbound lanes of Interstate 5 in Castle Rock, about 60 miles north of Portland, blocking the main artery connecting Seattle and Portland for hours and creating a 10-mile backup. The road has since reopened but significant backups remain.HOW TO WATCH FOX WEATHERThe hazardous conditions were the result of a potent winter storm that is part of a 1,500-mile system pummeling the Pacific Coast and is threatening a switchover to freezing rain later in the day. This is a developing story. FOX Weather will update with more information.