MISSOULA, Mont. -

The Montana Highway Patrol responded to a call at 1:50 p.m. on Friday for an overturned van west of Missoula.

This happened at milemarker 99 in the eastbound lanes.

A trooper tells NBC Montana the van missed a curve, went down the median at highway speeds, lost control, rolled and landed upside down.

The trooper reports that a 51-year-old woman from Huson was ejected and killed.  A 50-year-old Huson man had no life-threatening injuries.

The officer adds that the woman was not wearing a seatbelt.  The man was.

Investigators are trying to determine if speed or alcohol were factors.