The emergency services were called to the Route de la Charruee in the Castel, just before 08:00.
A spokesperson for the Joint Emergency Services Control Centre said the accident involved a vehicle and a pedestrian and that one person had been taken to hospital.
The St John Emergency Ambulance Service said it sent a ‘double crewed ambulance’ to the collision, with those first on the scene then requesting a paramedic also attend to help treat the casualty.
He had suffered multiple injuries and was treated at the scene before being taken to the Emergency Department of the Princess Elizabeth Hospital for further treatment.
The road was closed until around 11:00 as police enquiries into the accident continued.
Pictured top: Guernsey Police are investigating this morning’s accident.