RITZVILLE, Wash. -

The Washington State Patrol is investigating a fatal crash in the eastbound lanes of Interstate 90 near Ritzville early Thursday morning.

State troopers confirm three people were killed in a single-vehicle crash when their vehicle left the freeway and smashed into an overpass pillar outside of Ritzville while heading eastbound just before 5 a.m.

The driver, Gabriel Johnson, 20, and passengers 21-year-old Mary Werts and 19-year-old Trevor Hallman-Person were all killed in the crash.

For unknown reasons, the white Buick Centery left the roadway and hit the bridge support. Investigators said that the driver swerved several times into the shoulder before going over the guardrail and ultimately crashing into the pillar.

State Troopers are now investigating to determine what caused Johnson to swerve.

"My understanding is it was bare and dry at the time. Temperature was above freezing so I don't believe ice was a factor, but we are investigating all possibilities," WSP Sergeant Kris Schweigert said.

Both Johnson and Hallman-Person were wearing their seatbelts at the time of the crash. Werts was not.

Their families have been notified.