Idaho State Police said a truck driver who failed to stop at a stop sign caused an accident on State Highway 39 near American Falls.
The crash occurred Monday at about 8:30 a.m. when Star Pinder, 31, of Goodyear, Ariz., was traveling eastbound on Pleasant Valley Road in a 1996 GMC semi. She ran the stop sign at the intersection with the highway, ISP said.
Douglas Ruff, 50, of Aberdeen, was traveling southbound on the highway when he was struck by the oncoming truck.
Pinder was transported by air ambulance to Portneuf Medical Center in Pocatello. Pinder's 13-year-old passenger and Ruff were both transported to Power County Hospital by ground ambulance.
The highway was blocked briefly when the air ambulance was there, but all lanes are now open.