UHP said brief white-out conditions contributed to several slide-offs and four crashes in the canyon around 6:15 p.m. Monday. During the storm, troopers received word of a Cadillac driving the wrong way in traffic. That vehicle came upon a trooper who was already attending to jack-knifed semitrailer. The trooper had his red and blue patrol car lights on. The man hit the "front driver quarter panel to front driver quarter panel and then sideswiped the side of the trooper's vehicle before eventually stopping," the UHP stated.