BOONVILLE, Mo. -

One woman is dead and another is seriously injured following an early Friday morning car crash on Interstate 70 in Cooper County.

The Missouri State Highway Patrol says Heather L. Cole, 20, of Columbia, was driving eastbound around 2:30 a.m. when her car traveled off the left side of the road.

Troopers say the car crossed through the median cables into westbound traffic. Cole's car was then hit by a tractor trailer.

Cole was pronounced dead at the scene.

A passenger in the car, Sara K. Buxton, 24, also of Columbia, was seriously injured. She was transported by helicopter to University Hospital.

As of Friday afternoon, Buxton was listed in critical condition.

CRASH INVESTIGATION UNDERWAY

Investigators tell ABC 17 News they're puzzled as to how the crash happened. They said the investigation is on hold as they wait to talk with Buxton, hoping she can fill in the missing information.

Investigators believe Cole and Buxton were traveling back home to Columbia. They said they've done everything they can right now besides talking with Buxton.

What investigators hope to figure out is why the two women were driving back early in the morning, what caused Cole to lose control of the car, and how the car was able to get through the median cables.

“Whenever a vehicle hits the cables perpendicular perfectly, it runs right over top of the cables," said Missouri State Highway Patrol Sgt. Paul Reinsch. "I don't know in this case exactly how the vehicle struck. It will probably be part of the investigation what we learn how the vehicle got over the cables.”

Missouri Department of Transportation officials say the median cable barriers stop about 90 percent of vehicles that come into contact with them.