The crash took place around 6 a.m. Sunday northbound on I-95 just north of Exit 18 in Westport, said the Westport Fire Department on Facebook.
Arriving firefighters found a single car down an embankment and one occupant trapped inside. Firefighters extricated the occupant from the vehicle and then brought the person up the embankment utilizing a rope system, the department said.
All four of the occupants that were in the car at the time of the accident were transported to a local hospital.
The Fairfield Fire Department, Westport EMS, AMR and Norwalk Hospital EMS assisted on the scene.
The accident is under investigation by the Connecticut State Police.
Click here to follow Daily Voice Wilton and receive free news updates.