Ohio State Highway Patrol Lt. Christina J. Hayes, commander of the Springfield post, said a semi was traveling north on Prairie Road when a car pulled out in front of the truck at the two-way stop. The car was westbound on Mumper, Hayes said.
The semi hit the car, which ended up in a farm field. The truck jack-knifed.
The driver of the car was flown to Miami Valley Hospital with serious injuries, Hayes said.
The driver of truck was not injured.
Mumper Road was closed but was expected to reopen early this afternoon.