AUBURN, Wash. -- The driver of a car was killed when her vehicle crashed into a Washington State Patrol trooper's car early Thursday morning.

The trooper was outside of the vehicle and was not hurt, KIRO 7 Eyewitness News reported.

The trooper was investigating three single-car spinouts along an icy stretch of Highway 18 at 304th Street east of Auburn at about 3:20 a.m.

A car traveling eastbound at regular highway speeds came around a bend, struck the rear of the trooper's patrol car and flew off the road into a ditch, said KIRO 7 Eyewitness News reporter Jeff Dubois.

"I think that weather clearly was a contributing factor. It was very treacherous in all of southwest King County. After the snows and rains came, it froze. This stretch of roadway is extremely dangerous," said Sgt. T.J. Johnson of the Washington State Patrol.

The driver, a 61-year-old woman, was pronounced dead at the scene.

Eastbound lanes of Highway 18 in the area were closed during the investigation.

One of the drivers whose car spun out was arrested for driving under the influence, troopers said.