The States Police, Fire and Rescue Service and paramedics all attended the incident on Mont de la Pulente at 3.46 am on Sunday, after a black Ford Fiesta crashed into a cliff face at the southern end of the Five Mile Road.
Following the incident, a 21-year-old man was taken to hospital with serious injuries and five hours later was transferred to Southampton Hospital. He remains in the facility’s intensive care unit in a stable condition.
Two 19-year-old passengers and the 18-year-old driver sustained minor injuries.
The driver has since been interviewed and released on police bail.
Anyone who has any dash-camera footage or information regarding the crash should call the States police on 612612 or contact Crimestoppers on 0800 555111.