It happened on Route 13 between the Route 40 split and Llangollen Boulevard at 9:43 a.m.
Police say the driver of a red Toyota Camry lost control and veered from the left lane and crossed the roadway, striking a telephone pole before flipping over.
The telephone pole came crashing down on the front end of a Toyota Prius, driven by 76-year-old Allen Davis of New Castle. His wife was a passenger in the car but they were not injured.
A passenger in the Camry, only identified as a woman in her 40's, was transported from the accident scene to Christiana Hospital.
Police say the driver of the Camry fled. That person has not yet been identified.
Investigators say the car had been reported stolen two months ago.
The passenger was not charged.
Anyone with information is asked to call Delaware State Police Troop 9 at 302-378-5218 or Delaware Crime Stoppers at 1-800-TIP-3333. .