Man killed in Adelaide crash

A man has been killed after his car left the road and slammed into a tree south-east of Adelaide.

The Mitsubishi 4WD was travelling along Alexandrina Road, just south of Strathalbyn, when the driver lost control and crashed into a tree, just after 6am.

Emergency crews rushed to the scene but there was nothing they could do to save the driver - a 49-year-old man from Burnside - who was the only person in the vehicle.

Alexandrina Road was closed and traffic diverted around the scene as Major Crash Police tried to piece together exactly what led to the accident.

Investigators are appealing for anyone who saw the four-wheel drive prior to the crash to come forward.

The fatal crash comes a little over a week after high school sweethearts - 17-year-old Hayden Perkins and 18-year-old Mikayla Eastwood - were killed when their car slammed into another vehicle near Strathalbyn.

Tragically, the other vehicle was being driven by one of their teachers from the Eastern Fleurieu High School.