Emergency services were called at just after 11am yesterday (31 March) with reports a green Nissan Micra had left Ramsey Road, the B1040 near Ramsey St Mary.
Three people were taken to hospital for treatment, but the 68-year-old driver later died.
One of the passengers, a 34-year-old man, remains in hospital in a critical condition. The third person involved received minor injuries and has since been discharged.
No other vehicles are believed to have been involved.
The road was closed for several hours while the emergency services worked at the scene.
Anyone who witnessed the crash, has dashcam footage, or believes they saw the car beforehand, is asked to contact police via their web chat service: https://bit.ly/3vsiYDw or call 101, quoting incident 125 of 31 March.