SA woman killed in highway crash with tree

An Adelaide woman has died after her car left the road and hit a tree on a South Australian highway.

The 37-year-old Crafers woman died at the scene after the crash on the Riddoch Highway at The Gap, near Naracoorte, on Saturday morning.

The highway was closed and diversions were in place as major crash investigators examined the scene.

The death brings SA's road toll to 22 compared with 19 at the same time last year.