Investigators say just after 9 pm Saturday, a Toyota pickup was speeding westbound on 426 when the driver lost control and flipped.
The driver, believed to be in his 20's, was killed when the truck rolled down an embankment.
A passenger in the car was airlifted to CRMC for a serious hand injury but is expected to survive.
Investigators say the driver was not wearing a seatbelt and they're looking into whether drugs or alcohol may have played a factor in the solo-vehicle crash.