Port Elliot is a seaside town on South Australia’s Fleurieu Peninsula, about 80 kilometres from Adelaide. (ABC South East SA: Bec Whetham)

A man is in hospital with life-threatening injuries after a car crashed into a group of people outside a venue in a South Australian seaside town, police say.

According to SA Police, a blue Ford sedan collided with a group of people outside a licensed venue on North Terrace in Port Elliot just after 1:30am on Saturday, before leaving the area.

Police said a 37-year-old man suspected of driving the car returned a short time later and was arrested and taken to Christies Beach Police Station, where he is being interviewed by detectives.

A 22-year-old Hindmarsh Island man was flown to hospital in Adelaide with life-threatening injuries.

Four other people — a 21-year-old man from Goolwa Beach, a 37-year-old woman from Port Elliot, a 20-year-old woman from Inman Valley and a 30-year-old man from Blackwood — were all treated in hospital for minor injuries.

North Terrace, a main road connecting towns in the popular coastal region on the Fleurieu Peninsula, remains closed.