Deputies responded to a call that a woman had fallen from a vehicle on Grand Parkway SH 99 and FM 1485 at about 2 a.m.
Upon arrival, units found a Ford pickup truck parked in the U-turn lane and the victim on the ground. Deputies said that medical personnel performed CPR on the 26-year-old woman but could not revive her and pronounced her dead.
MCSO and the Montgomery County Precinct 4 Constables held the scene until the Department of Public Safety arrived.
The woman was reportedly in the truck with a friend who spoke to officials on the scene.
The friend told officials that the woman fell out the door as he was making a U-turn underneath Grand Parkway, according to DPS.
A field sobriety test done by DPS revealed that the man was intoxicated and was taken into custody. It is unclear if the man has been charged.
The truck was removed from the scene and transported to the District Attorney's Secure Inbound for further investigation.
The identities of the man and woman have not been released.