Authorities responded to Range Road and CR 800 S at the CSX Railroad crossing in Kingsford Heights at about 7:50 p.m., the sheriff's office said.
The car was sent into a cornfield 150 feet away from the crossing. Bystanders were able to get the boy out of the vehicle, but it took firefighters from the Kingsbury and Kingsford-Union Fire Departments 25 minutes to extricate the driver.
Both the woman, 36, and boy were airlifted to Parkview Hospital in Ft. Wayne, Indiana and were conscious and stable, the sheriff's office said.
Investigators said that the vehicle was waiting for a westbound train to pass by and when it did, the vehicle went around the gates and was struck by an approaching eastbound train.