A 6-year-old Gwinnett County boy died Saturday from injuries sustained after being struck by a vehicle, according to Gwinnett County Police spokesman Sgt. Brian Doan. Doan said police were notified around 9 p.m. of the incident in the 5000 block of Oak Grove Drive in Buford. The child and his 11-year-old brother were in the back of their father’s truck when the 6-year-old jumped out of the bed of the truck while the father was backing up in their driveway.