BURLINGTON, Iowa (AP) -

Relatives say an 18-year-old died after falling under a car he was holding onto while it was traveling down a gravel road on the southwest side of Burlington.

Clayton Connelly was injured around 1 a.m. Thursday. He was taken by private vehicle to a West Burlington hospital and then transferred to an Iowa City hospital. The Des Moines County Sheriff's Office says he died there. He'd lived in Burlington.

The Hawk Eye reports that Connelly's family said he'd been "gravel surfing" with friends. Gravel surfers hold onto vehicles and slide along the surface as the vehicles move down gravel roads. The Sheriff's Office says Connelly exited the vehicle while it was moving.