It happened around 7:00 Saturday evening on Centerville Road and West Red Clay Drive.
Authorities say a Jeep and a car collided, causing the Jeep to flip over.
17-year-old Anthony Maguire, a passenger inside the Jeep, was killed. Police say Maguire was not wearing his seatbelt at the time of the crash.
Three others were taken to Christiana Hospital for minor injuries.
Police are still investigating what caused the accident.
Maguire was a junior at A.I. DuPont High School. Red Clay School District spokesperson Pati Nash said on Monday that counselors were available at the school.