The accident happened in the southbound lanes of I-495 near Minquadale.
Police say the big rig clipped the car driven by 35-year-old Kimra Frett, and then kept going.
The car then hit a guard rail and rolled over.
The three people inside, Kimra Frett, 40-year old Sylvia Frett and 47-year old Troy Twyman were ejected from the car. Medics rushed them to Christiana Hospital in critical condition.
If you witnessed the hit and run, please call Delaware State Police.