A 28-year-old man has been arrested on suspicion of serious driving related offences.
Bailiwick Law Enforcement has confirmed, the individual was driving the vehicle at the time the fatal crash happened on Tuesday evening.
Two of those who were in the car are still at the Princess Elizabeth Hospital with serious but non-life threatening injuries.
At this time, both are in stable condition and neither will be flown off-island.
The other two people in the car suffered minor injuries and have been released from hospital.
Bailiwick Law Enforcement is also aware that misinformation is circulating on social media with regards to their investigation, such as whether a second person has died.
A spokesperson for Guernsey Police says "this is not the case".
The police have confirmed they are not going to release the name of the person who died in line with the family's wishes.
Enquiries are ongoing and officers would like to hear from anyone who has information regarding this incident.
The contacts for the investigation are Inspector Tom Marshall and PC James De La Mare.
They can be contacted on 01481 222222, or information can be reported anonymously through Crimestoppers on 0800 555 111.