The States police were called to the incident, involving a silver Renault Clio Sport, on Route de la Trinité at around 1.30am.
According to the force, the vehicle was heading south, down the hill, when it hit the wall of a property at the junction of Rue Jacques.
The driver and the passenger are both in a critical condition in hospital.
Anyone who witnessed the incident, who may have seen the vehicle prior to the collision or anyone who may have any relevant information is asked to call police on 612612 or contact Crimestoppers anonymously on 0800 555 111.
