In a terrifying and rare incident, a driver was killed in Fairfax County on Saturday when someone plunged from an overpass onto a vehicle.

The driver of the vehicle died at the scene on Interstate 66 from the impact, said Corinne Geller, spokeswoman for the Virginia State Police. The incident occurred about 4:20 p.m. in the eastbound lanes of the interstate, below the Cedar Lane overpass, near the Nutley Street exit, Geller said.

Neither the name nor the gender of the driver were given, pending the notification of relatives, she said.

The person who plunged from the overpass was taken to a hospital for treatment of injuries described as not life-threatening, she said. No name or age was given and he was described only as male.

It was not known why the plunge occurred. "We're not certain," Geller said.

Police are investigating the incident. The overpass appears to be about 20 to 30 feet above the highway.