Reports say a vehicle rear-ended a tractor trailer on the northbound lanes of Route 7 at Main Street in Stanton.
The 21-year-old male driver was trapped inside his vehicle.
A passing volunteer firefighter stopped at the scene and noticed the man was unconscious.
The firefighter gave the trapped driver mouth-to-mouth resuscitation.
Rescue crews arrived and freed the 21-year-old from the vehicle. He was transported to Christiana Hospital.
Delaware State Police are investigating.
The crash resulted in the closure of northbound Route 7.