A man was thrown from a car as it flipped over at the corner of Fifth Street and Minerva Wednesday night.
Police are investigating the crash, which happened at about 11:30 p.m.
Two people were in the car. Their names were not available.
Just one vehicle was involved.
The car crashed into a large retaining wall before rolling over onto its roof. The man who was ejected suffered serious head injuries.
The other man in the car was injured, but not as seriously. He was alert and talking to emergency crews as they helped him.
Both men were taken to the trauma center at Yale-New Haven Hospital.
Ambulance crews from Derby and Ansonia took the men to the hospital.
The people were taken to Yale-New Haven instead of nearby Griffin Hospital because Griffin is not a trauma center. Where people are taken is influenced by emergency response protocols and the nature of the injuries.
This story will be updated later.