LYNNWOOD, Wash. - Two Washington State Patrol cars parked on the shoulder of icy Highway 525 were totaled when an out-of-control SUV slammed into them Saturday morning.

The State Patrol says a sergeant and trooper had parked their patrol cars on the highway's northbound shoulder near Interstate 5 to investigate an earlier accident.

Suddenly a Ford Expedition began to lose control as it approached them. The SUV struck the concrete barrier, then plowed into the sergeant's patrol car.

The sergeant, who was outside in front of his car when it was hit, was pushed by the front of his own car briefly before jumping out of the way.

The Expedition spun around 180 degrees - accelerating and out of control - then crashed into the second patrol car. Both patrol cars were totaled, said WSP Trooper Keith Leary.

An injured thumb was the only injury to the trooper. The sergeant and the driver of the Expedition were unhurt.

Leary said the road conditions were "extremely icy" at the site of the crash, which apparently caught motorists off guard. He advised drivers to slow down when traveling on icy roads and to use extra caution.

"This is a perfect example why we need to be prepared and watch the weather closely this time of year," he said.

The State Patrol reported more than 20 collisions in the greater Seattle area in less than an hour and a half starting about 6:30 a.m.

One of those collisions, about two miles north of the WSP patrol car accident scene, involved a state Transportation Department sanding truck.