"The visibility simply went to zero," a state policeman told The Oregonian. "Obviously some people slowed down and others didn't."
Four people were killed in what appeared to be a chain reaction involving five trucks and 11 other vehicles in the eastbound lane. Two other multiple-vehicle accidents occurred in the westbound lanes near Woodpecker Truck Stop.
An electronic message board in the eastbound lanes at Boardman warned motorists of blowing dust and reduced visibility, but highway officials didn't know how long the sign had been lit before the accidents occurred. A westbound board was not functioning.
High winds are not uncommon to the area during the winter, but typically don't come this early in the year -- a time made particularly dangerous since the interstate is bordered by newly cultivated fields. The Weather Service had posted high wind warnings since Wednesday, but officials said Saturday's gusts - estimated at up to 85 mph in some areas - came too suddenly and without enough warning to close the freeway.
High winds and dust storms are also blamed for several other multiple-vehicle crashes in Eastern Oregon and Washington. Interstate 84, sections of Oregon 11 and 37, and U.S. 12 in Washington were closed for several hours Saturday.