Authorities are not sure why a driver on a north central Iowa highway lost control of her vehicle and crashed into a bridge shortly before noon on Tuesday.

The one vehicle accident happened late Tuesday morning at the 147 mile marker of Highway 20 in Webster City. According to an Iowa Highway Patrol report, an eastbound 1993 Chevrolet Lumina minivan driven by 54-year-old Michelle Salter of Fort Dodge lost control of the vehicle.

The minivan entered the right ditch and collided head on into a concrete bridge pillar. Salter died in the accident, which  remains under investigation.

(Reporting by Pat Powers, KQWC, Webster City)