A large rockslide crushed a car on Interstate 90 west of Snoqualmie Pass (search), leaving three 28-year-old women dead and closing the freeway to westbound traffic for more than half a day.

Janet J. Ishikawa of Lynnwood, driver of the 2004 Volvo, and passengers Heather E. Rider of Castle Rock and Janel A. Lindsey of Bothell died when rocks crashed into the westbound lanes of the state's principal east-west artery shortly after 1 a.m. Sunday, Washington State Patrol Trooper Kelly L. Spangler said.

Investigators believe the rockfall may have been triggered by recent rainfall.

The crash was one of several in which at least eight people died Sunday in the western part of the state. Two men and a woman died in a crash on the northern Key Peninsula (search) northwest of Tacoma, a 16-year-old Tacoma boy died after running a red light in Federal Way and a 29-year-old man died near Ferndale when he was thrown from his car after crashing through some mailboxes.

East of the Cascades, Luis Rangel Parra, 20, of Wapato, died early Sunday morning when he lost control of his Honda Civic in Union Gap and bounced off bridge railings on both sides of the street, state troopers said.

On I-90, state Transportation Department crews worked to remove debris and stabilize the steep slope near the Franklin Falls bridge about 2 miles west of the pass, and the freeway was closed to westbound traffic near Easton, about 70 miles southeast of Seattle and about 20 miles east of the crash site, until about 2:30 p.m.

During the closure traffic backed up for more than three miles, and some motorists opted instead for U.S. 2 over Stevens Pass to the north or U.S. 12 over White Pass to the south.

"This is a terrible tragedy for the people involved," state Transportation Secretary Doug MacDonald (search) said. "We know we have people inconvenienced, but we're not going to have somebody else come down here and meet the same fate these people did last night."

Geologists did not believe a slide was imminent in the area and stabilization efforts were concentrated along other highways that were believed to be more at risk, MacDonald said.

"We've had other ones elsewhere in the state we were working on first," he said. "We're always trying to do this work as we have the funds to do it."

In the Key Peninsula crash, Pierce County sheriff's Detective Ed Troyer said a car crossed the center line and collided with an oncoming car. Both drivers and a woman riding in the car that crossed the center died at the scene. Alcohol and speeding were factors in the crash, Troyer said.