Three dead on SA roads this week

A motorcycle rider killed in a collision with a car in Adelaide's south is the third person to die on South Australian roads this week.

The rider, a 44-year-old local man, died at the scene of the crash, which occurred in Seaview Downs about 4pm on Wednesday.

A 19-year-old driver was arrested at his home after allegedly fleeing a Largs Bay crash that left a 28-year-old male pedestrian dead on Tuesday night.

The accused was taken to hospital with minor injuries.

He has been charged with aggravated dangerous driving causing death, leaving the scene of a crash and driving while disqualified.

Meanwhile, a 27-year-old man died on Monday in the Royal Adelaide Hospital following a collision on the Yorke Peninsula on Sunday night.

The victim had to be cut free of the wreckage of his car after it crashed into another at an intersection, then crashed into a tree.

The South Australian road toll has risen to nine, four fewer than at the same time last year.