A 19-year-old student was killed in an accident when he was hit by an 18-wheeler Sunday night in Round Rock.

Todd Aaron Phelan went over the Interstate 35 overpass at State Highway 45 when he was struck by an 18-wheeler on his way down.

The Cedar Ridge High School student was taken to Round Rock Hospital where he died after a surgery.

The driver of the 18-wheeler stopped to help.

Investigators are not sure how Phelan went over other than to say he fell off the bridge at I-35.

Officials continue their investigation and say the incident is still classified as an accidental death.