Missoula, MT -

A 60-year-old Washington state woman was killed when her car drifted off Interstate 90 in western Montana and crashed into a tree.

The Montana Highway Patrol says the crash happened at 5:30 p.m. Thursday near Saltese, about 11 miles from the Idaho border.

Trooper Rich Hader says an initial investigation indicates the woman's car drifted off the road, hit a guardrail and then crossed both eastbound lanes before crashing into a tree in the median.

The woman died at the scene. Her name was being withheld while family members are notified.